Complementary SeleniumÂ·Â·Â·Iodine Halogen Bonding and Phenyl

Article pubs.acs.org/crystal

Complementary Selenium···Iodine Halogen Bonding and Phenyl Embraces: Cocrystals of Triphenylphosphine Selenide with Organoiodides Published as part of the Crystal Growth & Design virtual special issue on Halogen Bonding in Crystal Engineering: Fundamentals and Applications Hadi D. Arman,† Erin R. Rafferty,‡ Craig A. Bayse,*,‡ and William T. Pennington*,† †

Department of Chemistry, Clemson University, Clemson, South Carolina 29634-0973, United States Department of Chemistry & Biochemistry, Old Dominion University, Norfolk, Virginia 23529, United States

‡

ABSTRACT: Se···I Halogen bonding (XB) between triphenylphosphine selenide and organoiodides: 1,2-diiodotetrafluorobenzene (1,2-F 4 DIB), 1,4-diiodotetrafluorobenzene (1,4F4DIB), and tetraiodoethylene (TIE) has been used to assemble molecules into finite adducts, chains, and two-dimensional layers. Phenyl embraces involving the triphenylphosphine groups extend these moieties into additional dimensions, leading in two cases (1,4-F4DIB and TIE) to open structures, with filled or partially filled cavities. Comparison of structural parameters for 26 reported zigzag chains of embracing Ph3XY reveals that this synthon can adapt its registry to accommodate widely diverse structures. The strengths of the XB interactions were analyzed using natural bond orbital (NBO) theory, which provides an estimate of the energy of a donor−acceptor interaction (ΔEd→a) through localization of the molecular orbitals. Structures of 1:1 and 1:2 XB complexes of Ph3PSe with 1,2-F4DIB and 1,4-F4DIB were optimized at the DFT(B97-1)/BSI level. The bond distance and angles obtained are in reasonably good agreement with the experimentally observed structures.

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complexes,33 no studies of selenium-based halogen bonding with organohalogens have appeared. This is quite surprising, given the importance of selenium in the endocrinology of the thyroid.34,35 The potential exists for XB interactions between selenocysteine contained in the active site of type I iodothyronine deiodinase36 and the biologically important organoiodines, thyroxine (T4) and 3,3′,5-triiodothyronine (T3), and a recent modeling study has suggested a significant role for XB in the mechanism of deiodination of these thyroid hormones.37 Utilization of heavier congeners such as sulfur and selenium as XB acceptors has an added advantage over their lighter counterparts for crystal design. While hydrogen bonding interactions involving these elements are known,38−41 based on hard and soft acids and bases (HSAB) theory arguments, they should be quite weak relative to their halogen bonding interactions. Nitrogen and oxygen on the other hand are good acceptors for both interactions, leading to some uncertainty in which interaction will occur in a given substance. Several reports of competition studies have appeared,42−45 and elegant approaches to overcome this obstacle have been recently

INTRODUCTION Halogen bonding (XB), interactions between an electron-pair donor and a halogen atom as an electron-pair acceptor, has developed over recent years into a dependable tool for crystal design.1−7 Applications involving the directed use of this interaction have included separations,8−10 design of molecular conductors,11−13 crystals for optical second harmonic generation,14,15 layer-by-layer assembly of multicomponent polymer films,16 formation of reduced band gap mixed perovskites,17 liquid crystals,18−22 drug design,23 preorganization of dendritic molecules,24 and as templating agents for solid state polymorphic conversion.25−27 The importance of halogen bonding in biological systems is also being increasingly recognized.28−30 Almost all recent studies of halogen bonding have involved nitrogen or oxygen as XB acceptors. (We will use the convention that the electron-pair acceptor, in our case iodine, is the halogen bond donor, and the electron-pair donor, in our case selenium, is the halogen bond acceptor. This convention is also used for graph set analysis; that is, the iodine atom takes the place of the hydrogen bond donor, and the selenium corresponds to the hydrogen bond acceptor.31) Despite a few early structural reports of complexes of organoiodines with selenium-containing molecules32 and an extensive body of literature concerning selenium dihalogen and interhalogen © 2012 American Chemical Society

Received: October 10, 2011 Revised: May 4, 2012 Published: May 10, 2012 4315

dx.doi.org/10.1021/cg201348u | Cryst. Growth Des. 2012, 12, 4315−4323

Crystal Growth & Design

Article

reported,46−48 but utilization of softer donors bypasses the problem altogether. Herein we begin a systematic study of selenium-based halogen bonding with the report of the preparation and structural characterization of complexes of the selenium-based acceptor, triphenylphosphine selenide (Ph3PSe) with the organoiodine compounds: 1,2-diiodotetrafluorobenzene (1,2F4DIB), 1,4-diiodotetrafluorobenzene (1,4-F4DIB), and tetraiodoethylene (TIE). In addition to strong Se···I halogen bonds, these structures are also heavily influenced by phenyl embraces, concerted multiple edge-to-face interactions between aromatic rings.49,50

reaction products. All single crystal measurements were performed on a Rigaku AFC8S diffractometer with a Mercury CCD detector at room temperature (295 ± 1 K) for Ph3P = Se·1,4-F4DIB and 163 ± 1 K for the other complexes, with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). Data were collected to a maximum 2θ value of 52.7−52.8° in 0.5° oscillations (in ω) with two 25 s exposures (to identify detector anomalies). Corrections for Lorentz and polarization effects and absorption52 were applied to the data. The structures were solved by direct methods and refined by using full-matrix least-squares techniques. The unique carbon atom of one of the TIE molecules in 4Ph3PSe·TIE was disordered over two positions (70/30 distribution), and both carbon atoms were modeled with isotropic displacement parameters. This is a similar disorder to that observed in the crystal structure of TIE53 and is a consequence of the nearly square shape of the molecule (intramolecular I···I distances of 3.5 × 3.6 Å).54 A cavity centered about the inversion center at (0.5, 0.0, 0.5) was partially occupied by an additional but uncomplexed TIE molecule. Although the carbon atom could not be located, difference Fourier peaks corresponding to the iodine atoms were found and were refined with isotropic displacement parameters to an occupancy of 25%. All other non-hydrogen atoms of the complexes were refined anisotropically. Hydrogen atoms were included for each of the complexes in optimized positions with riding displacement parameters (20% greater than Ueq of host atom). Structure solution, refinement, and the calculation of derived results were performed with the SHELXTL-Plus package of computer programs.55 Crystallographic parameters are reported in Table 1.

Scheme 1

In addition to the structural work, a computational study was also performed. The strengths of the XB interactions were analyzed using natural bond orbital (NBO) theory, which provides an estimate of the energy of a donor−acceptor interaction (ΔEd→a) through localization of the molecular orbitals (MOs). Structures of 1:1 and 1:2 XB complexes of Ph3PSe with 1,2-F4DIB and 1,4-F4DIB were optimized at the DFT(B97-1)/BSI level. The bond distance and angles obtained are in reasonably good agreement with the experimentally observed structures.

Table 1. Crystal Data

formula Mw crystal system space group a (Å) b (Å) c (Å) β (°) V (Å3) Z Dcalc, g cm−3 μ, mm−1 transmission coefficients reflections collected reflections unique (Rmerge) R1a wR2b

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THERMAL ANALYSIS Differential scanning calorimetry analyses were carried out by using a TA Instruments SDT-2960 simultaneous DSC-TGA instrument. Sample masses ranged from 2 to 8 mg. The sample and reference were heated from 25 to 600 °C at a rate of 10 °C/min. Thermal events were characterized according to the positions of endotherms and exotherms in relation to weight loss. Thermal gravimetric analyses were performed on a Mettler-Toledo TGA/SDT851 analyzer. Sample masses ranged from 2 to 8 mg. All calculations were performed on data represented as percent loss of starting mass. For onset calculations, the samples were heated at a constant rate of 10 °C/min from 25 to 500 °C. Mass loss and onset calculations were performed by standard methods.

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X-RAY DIFFRACTION ANALYSIS Sample purity and identity was verified by X-ray powder diffraction analysis on a Scintag XDS/2000 theta−theta diffractometer at room temperature (295 ± 1 K) with Cu Kα1 radiation (λ = 1.54060 Å) and an intrinsic germanium solid-state detection system. Patterns from single crystal results with POWD12,51 were compared to those observed for bulk

Ph3PSe·1,2F4DIB

Ph3PSe·1,4F4DIB

4Ph3PSe·3TIEc

C24H15F4PSeI2 743.09 monoclinic P21/n (No. 14) 11.1579(18) 12.579(2) 16.975(3) 90.669(6) 2382.4(7) 4 2.07 4.28 0.83−1.00

C24H15F4PSeI2 743.09 monoclinic P21/c (No. 14) 9.6837(16) 23.452(4) 22.041(4) 101.694(3) 4901.7(14) 8 2.01 4.16 0.63−1.00

C78H60P4Se4I12 2959.78 monoclinic P21/n (No. 14) 22.196(2) 9.4096(11) 22.360(3) 91.266(5) 4668.9(9) 2 2.10 5.64 0.50−1.00

22251

46344

40963

4835 (0.083)

9983 (0.117))

9465 (0.079)

0.0546 (0.0865) 0.0841 (0.0937)

0.0622 (0.1336) 0.0994 (0.1149)

0.0775 (0.0895) 0.1665 (0.1719)

a R1 = Σ∥Fo| − |Fc∥/Σ|Fo| for observed data (I > 2σ(I)); number in parentheses is for all data. bwR2 = {Σ[w(Fo2 − Fc2)2]/Σ[w(Fo2)2]}1/2 for observed data (I > 2σ(I)); number in parentheses is for all data. c The formula for this compound, and parameters derived from it, do not include TIE in the partially occupied site.

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Article

THEORETICAL METHODS

Table 2. Thermal Behavior of Ph3PSe, XB Donors, and Their Cocrystals

Geometries were optimized with PQS version 3.356 at the DFT level using the B97-157 exchange-correlation functional and the following basis set (BS1). Relativistic effective core potential basis sets supplemented with diffuse and polarization functions were used for S, Se, Br, and I.58,59 Dunning triple-ζ basis sets were used for all first-row atoms.60 Hydrogen was represented by the Dunning double-ζ basis.61 Frequency calculations were used to confirm each structure as a minimum on the potential energy surface.

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compound

EXPERIMENTAL SECTION

Triphenylphosphine selenide, 1,4- diiodotetrafluorobenzene, 1,2diiodotetrafluorobenzene, and tetraiodoethylene were purchased from either Aldrich Chemical Co. or ACROS Organics and were used as received. Solvents were acquired from commercial sources. Carbon and hydrogen elemental analysis were performed by Atlantic Microlabs, Norcross, GA. Synthesis of Ph3PSe·1,2-F4DIB. Triphenylphosphine selenide (0.010 g; 0.029 mmol) and 1,2-diiodotetrafluorobenzene (0.012 g; 0.030 mmol) were dissolved in methylene chloride (∼ 5 mL). Slow evaporation of the solvent yielded 0.016 g of Ph3PSe·1,2-F4DIB as colorless crystals suitable for X-ray diffraction analysis (76% yield). Elemental analysis, calculated (observed): %C 38.79 (40.07), %H 2.03 (2.12). Synthesis of Ph3PSe·1,4-F4DIB. Triphenylphosphine selenide (0.011 g; 0.032 mmol) and 1,4-diiodotetrafluorobenzene (0.013 g; 0.032 mmol) were dissolved in methylene chloride (∼ 5 mL). Slow evaporation of the solvent yielded 0.019 g of Ph3PSe·1,4-F4DIB as colorless crystals suitable for X-ray diffraction analysis (78% yield). Elemental analysis, calculated (observed): %C 38.79 (39.00), %H 2.03 (2.07). Synthesis of 4Ph3PSe·3TIE. Triphenylphosphine selenide (0.010 g; 0.029 mmol) and tetraiodoethylene (0.021 g ; 0.022 mmol) were dissolved in methylene chloride (∼5 mL). Slow evaporation of the solvent yielded 0.019 g of 4Ph3PSe·3TIE as colorless crystals suitable for X-ray diffraction analysis (94% yield). Elemental analysis, calculated (observed): %C 31.65 (32.70), %H 2.04 (2.19). X-ray crystallographic information files (CIF) for Ph3PSe·1,2F4DIB (CCDC660559), Ph3PSe·1,4-F4DIB (CCDC660406), and 4Ph3PSe·3TIE (CCDC660560), have been deposited with the Cambridge Crystallographic Data Centre.

melting point (°C)

thermal onset (°C)

mass loss (%)a

Ph3PSe 1,2-F4DIB 1,4-F4DIB TIE Ph3PSe·1,2F4DIB

186−190b 49−50b 108−110b 191−193b 128c

310 133 160 257 98

100 100 100 100 52 (54)

Ph3PSe·1,4F4DIB

123c

255 105

45 (46) 50 (54)

4Ph3PSe·3TIE

122c

275 broad

49 (46) 100

a Mass loss is given as experimental (theoretical). bVendor-supplied data. cMelting onset, DSC.

All three cocrystals exhibit strong Se···I halogen bonding interactions with contact distances well below the sum of van der Waals radii (nonspherical vdw ellipsoids assumed: Se 2.15 Å; I 1.76 Å).68 The angles at iodine are approximately linear, and those at selenium are roughly tetrahedral, as would be expected for electron-pair donation from the selenium to the iodine. The values agree well with those of reported structures, 1,4-diselane·diiodoacetylene67 and 1,4-diselane·iodoform.69 Structure of Ph3PSe·1,2-F4DIB. The compound crystallizes as a simple adduct (D) with both molecules occupying general positions within the unit cell (Figure 1). The iodine atom not involved in Se···I halogen bonding interacts with a phenyl ring of the Ph3PSe molecule, as well as with a 1,2F4DIB molecule of a neighboring adduct related by an inversion center at (1/2, 1/2, 0) with contact distances (I···Caromatic) ranging from 3.754(7) to 3.858(7) Å. A sextuple phenyl embrace50,70,71 between phenyl rings of Ph3PSe links molecules related by an inversion center at (1/2, 1/2, 1/2) with a P···P distance of 6.602(4) Å. These latter two interactions couple to form weakly associated chains of adducts running parallel to the c-axis (Figure 2). Structure of Ph3PSe·1,4-F4DIB. The asymmetric unit consists of two unique triphenylphosphine selenide molecules and four half-1,4-F4DIB molecules (each situated about an inversion center). One XB acceptor and two of the XB donors form infinite halogen bonded chains (Figure 3a) running parallel to [2 0 1], with a binary graph set description of C21(14), while another XB donor links two acceptor molecules into a 1:2 adduct (Figure 3b), with a unitary graph set description of D22(7). In addition, one 1,4-F4DIB molecule in the lattice (situated about an inversion center at (1/2, 0, 0)) is not complexed to any acceptor molecule. Chains related by translation along the a-axis are interwoven with adducts, such that 1,4-F4DIB molecules of the adducts form segregated stacks with alternating 1,4-F4DIB molecules of the chains. These stacks run parallel to the a-axis along the line (x, 0, 1/2), with individual molecules situated about inversion centers separated by a distance of a/2 (4.842 Å). Noncomplexed 1,4-F4DIB molecules fill gaps to form similar segregated stacks running along (x, 0, 0). The resulting layer has a core of XB donor stacks with triphenylphosphine groups oriented to the top and bottom surfaces (see Figure 4). Use of the term “layer” is not meant to imply strong interaction between the 1,4-F4DIB molecules of the two unique stacks. On the contrary, these molecules exhibit no indication of attractive

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RESULTS AND DISCUSSION Analysis of the thermal behavior of halogen bonded cocrystals provides a reliable indication of their relative stability.62 Relevant thermal information for the pure halogen bond donors, acceptors and their cocrystals is provided in Table 2. Cocrystals of Ph3PSe with 1,2-F4DIB and 1,2-F4DIB decompose cleanly in two well-defined thermal events, corresponding to loss of the XB-donor at lower temperature. This conclusion is supported by observation of an endotherm at ∼360 °C, corresponding to the boiling point of Ph3PSe. Decomposition of the TIE cocrystal occurs as a poorly defined event over a very broad temperature range. This is probably due to the very similar melting points of the two components. Observation of a DSC endotherm at ∼360 °C suggests that, as in the other cocrystals, the XB donor is lost first, followed by the XB acceptor. Derived structural parameters are given in Table 3. Graph set analysis similar to that developed to define hydrogen bonding patterns,63−65 with modification for halogen bonding,66,67 is used to describe structural motifs. 4317



Article

Table 3. Structural Parameters (Å, °) Ph3PSe·1,2-F4DIB

Ph3PSe·1,4-F4DIB

intramolecular C−Ia (Å)

2.095(7)

2.092(8) 2.078(8) 2.082(8)

C−Ib (Å)

2.082(7)

2.043(10)

P−Se (Å)

2.1152(19)

P−Crange (Å) P−Caveragec (Å) Se−P−Crange (°) Se−P−Caveragec (°) halogen bonding Se···I (Å)

1.800(7)−1.811(7) 1.807(7) 112.4(2)−113.8(2) 113.0(7)

2.127(2) 2.107(2) 1.802(8)−1.819(8) 1.813(8) 111.3(3)−113.7(3) 112.5(8)

3.4354(10)

3.4944(11) 3.6841(12) 3.4224(13)

C−I···Se (°)

170.92(19)

171.4(2) 154.9(3) 166.5(2)

P−Se···I (°)

100.10(6)

113.01(7) 88.90(6) 112.60(7)

I···Se···I (°) Phenyl embraces P···P (Å)

126.00(3)

6.602(4)

6.476(4) 6.502(4) 96.52(8)

4.981(11)−5.058(11) 5.03(4)

4.784(12)−4.988(13) 4.89(7)

P···P···P (°) (XPh···XPh′)drange (Å) (XPh···XPh′)caverage (Å)

4Ph3PSe·3TIE 2.119(14) 2.107(15) 2.105(12) 2.115(16), 2.09(3)e 2.098(12) 2.104(16), 2.12(3)e 2.125(3) 2.126(3) 1.801(11)−1.824(12) 1.815(12) 112.1(4)−113.2(4) 112.6(4) 3.6483(15) 3.4510(15) 3.4519(14) 3.5573(15) 169.9(4) 172.6(4) 171.3(3) 170.0(5), 163.1(9)e 113.73(9) 113.17(9) 104.99(9) 108.60(9) 130.48(4) 140.63(4) 6.318(5) 6.365(5) 96.27(9) 96.31(9) 4.70(2)−5.10(2) 4.84(14)

a

Complexed iodine atom. bNoncomplexed iodine atom. cThe standard deviation reported is the larger of either the sigma based on the range of values averaged or the maximum experimental uncertainty of the parameters. dXPh represents the centroid of a phenyl ring bonded to phosphorus. e The two parameters involve the major or minor component of a disordered carbon atom, respectively (see Experimental Section).

Figure 2. Chains of Ph3PSe·1,2-F4DIB adducts (Se···I interactions are shown as heavy dashed lines) linked by I···Caromatic interactions (light dashed lines) and sextuple phenyl embraces (P···P solid line).

would bring them into closer proximity to a selenium atom of an adduct. Assuming this could lead to formation of a second Se···I halogen bond, as is observed for the other selenium atom, a similar chain structure should form. As with many crystal structures, the subtle interplay of packing forces which lead to the observed structure is difficult to comprehend. The layers stack along the b-axis, with adjacent layers related by a 21 operation (Figure 5). The triphenylphosphine groups on the top and bottom surfaces of the layers mesh in phenyl embraces to form zigzag chains of triphenylphosphine selenides (vide infra), also running parallel to the a-axis of the cell.

Figure 1. Ph3PSe·1,2-F4DIB adduct (50% probability ellipsoids) showing the Se···I halogen bonding interaction (heavy dashed line) and the π···I interaction (light dashed lines).

interaction. The dihedral angle between adjacent molecules of the donor/chain stacks is 17.7°, and they make angles of 37.9 and 42.0°, respectively with the a-axis. The corresponding angles for the noncomplexed molecule/chain stacks are 17.8, 52.4, and 38.4°. It is interesting to note that clockwise rotation of the noncomplexed 1,4-F4DIB molecules about the stack axis 4318



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Figure 3. Thermal ellipsoid plot (50% probability) showing selected atomic labeling for (a) an infinite chain consisting of one Ph3PSe molecule linked to two unique 1,4-F4DIB molecules, each situated about inversion centers (atoms labeled with “A” generated by (−x, −y, −z); atoms labeled with “B” generated by (2 − x, −y, 1 − z)). (b) An adduct situated about an inversion center consisting of two Ph3PSe molecules linked by a single 1,4-F4DIB molecule (atoms labeled with “C” generated by (−1 − x, 1 − y, −z)). A noncomplexed F4DIB molecule, situated about an inversion center at (1/2, 0, 0), is not shown.

Figure 5. Crystal packing of Ph3PSe·1,4-F4DIB viewed down the aaxis.

Structure of 4Ph3PSe·3TIE. The asymmetric unit consists of two unique triphenylphosphine selenide molecules and three half-TIE molecules (each situated about an inversion center). Se···I Halogen bonding links triphenylphosphine selenide with TIE to form infinite chains running parallel to both the a- and c-axes, each with binary graph set description of C42(10). Intersection of the chains forms a two-dimensional layer of fused octameric rings with a ternary graph set description of R168(38), as seen in Figure 6. The corners/ junctions of the rings are formed by TIE molecules which halogen bond to selenium atoms through all four iodine atoms, and the size of the ring is expanded by TIE molecules that link the junctions through halogen bonding involving only two of the four iodine atoms. The center of each ring is partially occupied (∼25%) by a noncomplexed TIE, with no contacts shorter than vdw sums.72 Layers stack to complete the

structure, with phenyl embraces being the dominant interlayer interaction. These embraces form zigzag triphenylphosphine selenide chains, similar to those in the 1,4-F4-DIB cocrystal. Adjacent layers are related by an n-glide operation, which places the partially occupied cavity directly over the four-coordinate TIE and places a two-coordinate TIE of one chain over a twocoordinate TIE of the other (Figure 7). This results in segregated stacks of TIE molecules running parallel to a unit cell axis (in this case the b-axis), similar to those in the 1,4F4DIB complex. Likewise, one of the stacks contains noncomplexed TIE molecules in alternating sites of one of the stacks, as was also observed for the 1,4-F4DIB complex, but in this case the TIE molecule apparently diffuses out of the crystal easily, as these sites are only about 20% occupied. This opens the possibility of diffusing alternative π-stacking ligands into the

Figure 4. Layer of interwoven chains and adducts for Ph3PSe·1,4-F4DIB. Dashed lines highlighted in yellow define the infinite chain; dashed lines highlighted in blue define the adducts. 4319



Article

sequence of local interactions, namely, repeated 5P1Y, rather than alternating 6P and 4P2Y...”75 The chains observed in the cocrystals reported here do in fact have this alternate set of 5P1Y interactions. A CSD search76 revealed 26 Ph3XY structures (X = Si, Ge, Sn, Y = Cl, Br, I or X = P, As, Sb, Y = S, Se) with 5P1Y chains.77 While moieties linked through 6PE and 4P2Y interactions are often related by inversion centers, 5P1Y chains are typically propagated along a 2-fold screw axis (21) or by pseudo-21 operations to form polar zigzag chains. All of the present cases are centrosymmetric, with polar chains extending in both directions. Figure 8b is based on 10 representative examples of these and illustrates the similarity among them and with the chains in the 1,4-F4DIB and TIE cocrystals. For comparison to structural data given in Table 3, the values for the 26 5P1Y structures are P···Prange = 5.833− 6.330 Å, P···Paverage = 6.13(11) Å; P···P···Prange = 99.11− 110.41°, P···P···Paverage = 104(3)°; (XPh···XPh′)range = 4.604− 5.086 Å, (XPh···XPh′)average = 4.81(7) Å. Corresponding values for the 1,4-F4DIB and TIE cocrystals lie outside these ranges, but the majority of the known examples are relatively simple structures in which Ph3XY is not strongly linked to other extended structures. That the zigzag Ph3PSe chains can dramatically adjust their registry to accommodate halogen bonding interactions with the organoiodine acceptors and yet maintain the P5Y1 packing makes this a valuable complementary synthon for crystal design. DFT Calculations. In the context of molecular orbital (MO) theory, XB interactions are described in terms of mixing the lone pair MO on the XB-acceptor with the empty R−X σ* MO on the XB-donor.37 The strengths of the XB interactions can be analyzed using NBO theory,78 which provides an estimate of the energy of a donor−acceptor interaction (ΔEd→a) through localization of the MOs. To determine these interaction energies, structures of 1:1 and 1:2 XB complexes of Ph3PSe with 1,2-F4DIB and 1,4-F4DIB were optimized at the DFT(B97-1)/BSI level. Bond distances and angles (Table 4) are in reasonably good agreement with the experimentally observed structures. The Se−I bond distances are less than the sum of the van der Waals radii indicative of the XB interaction but are found at longer distances than the Me2Se·IC6F5 complex calculated using the B3PW91 xc functional.37 Populating the σ(C−I)* MO increases the C−I distance by 0.024−0.031 Å relative to the uncomplexed halobenzenes and is reflected in the transfer of electron density from Se to I as calculated by Natural Population Analysis (NPA) charges (Table 4). The I−Se−I bond angle of ∼100° in the 1:2 complexes is consistent with donation of electron density from both Se p-type lone pairs. The calculated C−I−Se and I−Se−I bond angles are closer to an idealized molecular picture (180° and 90°, respectively) and the deviations from the X-ray structure could be attributed to constraints required by formation of the extended network. The ΔEd→a donor− acceptor energies for the 1:1 and 1:2 complexes (Table 4) are slightly weaker than those calculated for Me2Se with C6F5I and a truncated model of thyroxine calculated in a similar basis set using the B3PW91 xc functional.37 Given the greater electron density on the Se center of Ph3PSe, the weaker interactions may be attributed to steric interactions between the Ph groups of Ph3PSe and the halobenzenes. To reinforce the MO picture of XB interactions, Se···I Wiberg bond indices (WBI)79 were calculated as the sum of the squares of the XB contributions to the NBO Kohn−Sham density. These WBIs (Table 4) are approximately one tenth of the value of a single

Figure 6. Layer of fused octameric rings of 4Ph3PSe·3TIE viewed down the b-axis. The 25% occupancy TIE molecules have iodine atoms represented with open circles, and no carbon atoms are shown.

Figure 7. Crystal packing of 4Ph3PSe·3TIE viewed down the b-axis.

empty cavities, which might lead to interesting electronic properties. Zigzag Chains of Phenyl Embracing Ph 3 PSe Molecules. The zigzag chains of embracing Ph3PSe molecules, found in both the 1,4-F4DIB and TIE cocrystals, are nearly identical (Figure 8a) and are similar to those found in numerous Ph4P+, Ph3PMe+, and Ph3PCl+ salts.73−75 Adjacent Ph4P+ cations are linked through 6-fold phenyl embraces (6PE), while those of Ph3PMe+ and PH3PCl+ are linked through a 6-fold phenyl embrace to one neighbor and through a pseudo-6PE involving four phenyl rings and two hetero groups, Me or Cl. Dance designates the latter as a 4P2Y chain and suggests that these cations, “could have an alternate 4320



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Figure 8. Overlapped drawings showing the similarity of the P51Y chains for (a) Ph3PSe·1,4-F4DIB and 4Ph3PSe·3TIE. (b) 10 representative examples of P51Y chains taken from ref 75.

Table 4. DFT(B97-1) Bond Distances (Å), Angles (°), NBO Donor−Acceptor Energies (ΔEd→a; kcal/mol), NPA Charges (qSe and qI), and Se···I Wiberg Bond Indices (WBI) for 1:1 and 1:2 Complexes of Ph3PSe with 1,2-F4DIB (ortho) and 1,4-F4DIB (para) d(C−I)a 1:1 ortho 1:1 para 1:2 ortho 1:2 para

2.113 2.105 2.112 2.112 2.100

(+0.029) (+0.031) (+0.028) (+0.028) (+0.026)

d(Se···I)

d(P = Se)

∠(I−Se−P)

∠(C−I−Se)

3.422 3.422 3.427 3.425 3.458 3.472

2.168 2.168 2.184

101.36 98.50 101.59 100.94 100.45 96.23

179.28 178.27 176.49 177.36 178.22 177.46

2.185

∠(I−Se−I)

115.39 105.60

ΔEd→a

qSea

7.84 7.76 6.49 6.30 8.05 8.13

−0.491 (−0.023) −0.495 (+0.019) −0.487 (+0.027) −0.494 (+0.020)

2.098 (+0.024) a

0.263 0.267 0.268 0.269 0.277

qIa

WBI

(−0.021) (−0.023) (−0.016) (−0.015) (−0.013)

0.102 0.105 0.083 0.081 0.085 0.088

0.274 (−0.016)

Values in parentheses are difference in bond distances and NPA charges relative to the uncomplexed molecules.

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CONCLUSION Heavier congeners of nitrogen and oxygen serve as excellent halogen bond acceptors to organoiodines. Depending on the dimensionality and number of donor sites, triphenylphosphine selenide forms adducts, chains, and layers through significantly strong halogen bonds to iodine. This acceptor also offers 5P1Y phenyl embraces to form polar zigzag chains, further increasing the dimensionality of the halogen bond architectures. Comparison of these chains reveals their ability to adapt their registry to accommodate a wide range of cocrystalline components. That two of the three cocrystals include full or

bond demonstrating that the XB interaction is not purely electrostatic but involves a significant bonding contribution. The ΔEd→a and WBI values for the 1:2 complexes are slightly lower than those for the 1:1 complexes as would be expected for the depletion of electron density in the XB-acceptor atom with the formation of two interactions. However, the magnitude of these interactions demonstrates that orthogonal MOs on the same XB-acceptor atom are able to donate to multiple XB-donors equally. 4321



Article

(21) Xu, J.; Liu, X.; Lin, T.; Huang, J.; He, C. Macromolecules 2005, 38, 3554−3557. (22) Nguyen, H. L.; Horton, P. N.; Hursthouse, M. B.; Legon, A. C.; Bruce, D. W. J. Am. Chem. Soc. 2004, 126, 16. (23) Lu, Y.; Shi, T.; Wang, Y.; Yang, H.; Yan, X.; Luo, X.; Jiang, H.; Zhu, W. J. Med. Chem. 2009, 52, 2854−2862. (24) Metrangolo, P.; Meyer, F.; Pilati, T.; Proserpio, D. M.; Resnati, G. Cryst. Growth Des. 2008, 8, 654−659. (25) Padgett, C. W.; Walsh, R. D.; Drake, G. W.; Hanks, T. W.; Pennington, W. T. Cryst. Growth Des. 2005, 5, 795−807. (26) Rimmer, E. L.; Bailey, R. D.; Hanks, T. W.; Pennington, W. T. Chem.Eur. J. 2000, 6, 4071−4081. (27) Bailey, R. D.; Grabarczyk, M.; Hanks, T. W.; Pennington, W. T. J. Chem. Soc., Perkin 2 1997, 2781−2786. (28) Auffinger, P.; Hays, F. E.; Westhof, E.; Ho, P. S. Proc. Natl. Acad. Sci. U.S.A. 2004, 48, 16789−16794. (29) Battistutta, R.; Mazzorana, M.; Sarno, S.; Kazimierczuk, Z.; Zanotti, G.; Pinna, L. A. Chem. Biol. 2005, 12, 1211−1219. (30) de Jong, R. M.; Kalk, K. H.; Tang, L.; Janssen, D. B.; Dijkstra, B. W. J. Bacteriol. 2006, 188, 4051−4056. (31) Metrangolo, P.; Pilati, T.; Resnati, G. CrystEngComm 2006, 8, 946. (32) Hassel, O. Science 1970, 170, 497−502 and references therein.. (33) Pennington, W. T.; Hanks, T. W.; Arman, H. D. Structure and Bonding Series: Halogen Bonding, Fundamentals and Applications; Resnati, G.; Metrangolo, P., Eds.; Springer: London, 2007, Chapter 3, and references therein. (34) Beckett, G. J.; Arthur, J. R. J. Endocrinol. 2005, 184, 455−465. (35) Köhrle, J. Thyroid 2005, 15, 841−853. (36) Berry, M. J.; Banu, L.; Larsen, P. R. Nature 1991, 349, 438−440. (37) Bayse, C. A.; Rafferty, E. R. Inorg. Chem. 2010, 49, 5365−5367. (38) Krepps, M. K.; Parkin, S.; Atwood, D. A. Crystal Growth Des 2001, 1, 291−297. (39) Steiner, T. J. Mol. Struct. 1998, 447, 39−42. (40) Wendland, F.; Nather, C.; Schur, M.; Bensch, W. Z. Naturforsch., B: Chem. Sci. 1998, 53, 1144−1148. (41) Wu, R.; Hernández, G.; Odum, J. D.; Dunlap, R. B.; Silks, L. A. Chem. Commun. 1996, 1125−1126. (42) Aakeröy, C. B.; Fasulo, M.; Schultheiss, N.; Desper, J.; Moore, C. J. Am. Chem. Soc. 2007, 129, 13772−13773. (43) Bouchmella, K.; Boury, B.; Dutremez, S. G.; van der Lee, A. Chem, Eur. J. 2007, 13, 6130−6138. (44) Varughese, S.; Pedireddi, V. R. Chem.Eur. J. 2006, 12, 1597− 1609. (45) Corradi, E.; Meille, S. V.; Messina, M. T.; Metrangolo, P.; Resnati, G. Angew. Chem., Int. Ed. 2000, 39, 1782−1785. (46) Aakeröy, C. B.; Desper, J.; Helfrich, B. A.; Metrangolo, P.; Pilati, T.; Resnati, G.; Stevenazzi, A. Chem. Commun. 2007, 4236−4238. (47) Zhu, S.; Xing, C.; Xu, W.; Li, Z. Tetrahedron. Lett. 2004, 45, 777−780. (48) Saha, B. K.; Nangia, A.; Jaskólski, M. CrystEngComm 2005, 7, 355−358. (49) Dance, I.; Scudder, M. J. Chem. Soc. Chem. Commun. 1995, 1039−1040. (50) Dance, I.; Scudder, M. Chem.Eur. J. 1996, 2, 481−486. (51) Smith, D. K.; Nichols, M. C.; Zolensky, M. E. In POWD12, A Fortran IV Program for Calculating X-ray Powder Diffraction Patterns; Department of Geosciences, The Pennsylvania State University: University Park, PA, 1983. (52) Jacobson, R. A. REQABS, subroutine of Crystal Clear; Rigaku/ MSC: The Woodlands, TX, 1999. (53) Pawley, G. S. Acta Crystallogr. 1978, B34, 523−528. (54) Bailey, R. D.; Hook, L. L.; Watson, R. P.; Hanks, T. W.; Pennington, W. T. Cryst. Eng. 2000, 3, 155−171. (55) Sheldrick, G.M. SHELXTL, Crystallographic Computing System; Nicolet Instruments Division: Madison, WI, 1986. (56) PQS, version 3.3; Parallel Quantum Solutions: Fayetteville, AR, 2007.

partial occupancy noninteracting halogen bond donor molecules within the lattice offers the potential for guest exchange. This avenue is under exploration. Continuing work will focus on bis-diphenylphosphine chalcogenides, which combine the potential for phenyl embraces with two acceptor sites for additional structure extension. Of particular interest will be the effect of odd/even methylene bridges on crystal packing and the possibility of chelation with acceptors possessing long methylene bridges.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected] (W.T.P.). E-mail: [email protected] (C.A.B). Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS W.T.P. acknowledges helpful discussion with Professor Ian Dance of the University of New South Wales. C.A.B. is grateful for funding from the National Science Foundation (CHE0750413).

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REFERENCES

(1) Metrangolo, P.; Resnati, G. Chem.Eur. J. 2001, 7, 2511−2519. (2) Metrangolo, P.; Neukirch, H.; Pilati, T.; Resnati, G. Acc. Chem. Res. 2005, 38, 386−395. (3) Metrangolo, P.; Resnati, G.; Pilati, T.; Liantonio, R.; Meyer, F. J. Polym. Sci., Part A: Polym. Chem. 2007, 45, 1−15. (4) Metrangolo, P.; Meyer, F.; Pilati, T.; Resnati, G.; Terraneo, G. Angew. Chem., Int. Ed. 2008, 47, 6114−6127. (5) Rissanen, K. CrystEngComm 2008, 10, 1107−1113. (6) Metrangolo, P.; Resnati, G.; Pilati, T.; Biella, S. Structure and Bonding Series: Halogen Bonding, Fundamentals and Applications; Resnati, G., Metrangolo, P., Eds.; Springer: London, 2008; Chapter 4, p 126. (7) Fourmigué, M. Curr. Opin. Solid State Mater. Sci. 2009, 13, 36− 45. (8) Farina, A.; Meille, S. V.; Messina, M. T.; Metrangolo, P.; Resnati, G.; Vecchio, G. Angew. Chem., Int. Ed. 1999, 38, 2433−2436. (9) Gattuso, G.; Pappalardo, A.; Parisi, M. F.; Pisgatti, I.; Crea, F.; Liantonio, R.; Metrangolo, P.; Navarrini, W.; Resnati, G.; Pilati, T.; Pappalardo, S. Tetrahedron 2007, 63, 4951−4958. (10) Metrangolo, P.; Carcenac, Y.; Lahtinen, M.; Pilati, T.; Rissanen, K.; Vij, A.; Resnati, G. Science 2009, 323, 1461−1464. (11) Yamamoto, H. M.; Yamaura, J. I.; Kato, R. J. Am. Chem. Soc. 1998, 120, 5905−5913. (12) Kato, R.; Imakubo, T.; Yamamoto, H.; Maeda, R.; Fujiwara, M.; Yamaura, J. I.; Sawa, H. Mol. Cryst., Liq. Cryst. 2002, 380, 61−68. (13) Fourmiqué, M.; Batail, P. Chem. Rev. 2004, 104, 5379−5418. (14) Cariati, E.; Forni, A.; Biella, S.; Metrangolo, P.; Meyer, F.; Resnati, G.; Righetto, S.; Tordin, E.; Ugo, R. Chem. Commun. 2007, 2590−2592. (15) Sarma, J. A. R. P.; Allen, F. H.; Hoy, V. J.; Howard, J. A. K.; Thaimattam, R.; Biradha, K.; Desiraju, G. R. Chem. Commun. 1997, 101−102. (16) Wang, F.; Ma, N.; Chen, Q.; Wang, W.; Wang, L. Langmuir 2007, 23, 9540−9542. (17) Sourisseau, S.; Louvain, N.; Bi, W.; Mercier, N.; Rondeau, D.; Boucher, F.; Buzaré, J. V.; Legein, C. Chem. Mater. 2007, 19, 600−607. (18) Bruce, D. W.; Metrangolo, P.; Meyer, F.; Präsang, C.; Resnati, G.; Terraneo, G.; Whitwood, A. C. New J. Chem. 2008, 32, 477−482. (19) Xu, J.; Liu, X.; Ng, J. K. P.; Lin, T.; He, C. J. Mater. Chem. 2006, 16, 3540−3545. (20) Metrangolo, P.; Präsang, C.; Resnati, G.; Liantonio, R.; Whitwood, A. C.; Bruce, D. W. Chem. Commun. 2006, 3290−3292. 4322



Article

(57) Hamprecht, F. A.; Cohen, A. J.; Tozer, D. J.; Handy, N. C. J. Chem. Phys. 1998, 109, 6264−6271. (58) Hurley, M. M.; Pacios, L. F.; Christiansen, P. A.; Ross, R. B.; Ermler, W. C. J. Chem. Phys. 1986, 84, 6840−53. (59) Wadt, W., R.; Hay, P. J. J. Chem. Phys. 1985, 82, 284−298. (60) Dunning, T. H. J. Chem. Phys. 1971, 55, 716−723. (61) Dunning, T. H. J. Chem. Phys. 1970, 53, 2823−33. (62) Jay, J. I.; Padgett, C. W.; Walsh, R. D. B.; Hanks, T. W.; Pennington, W. T. Cryst. Growth Des. 2001, 1, 501−507. (63) Etter, M. C. Acc. Chem. Res. 1990, 23, 120−126. (64) Etter, M. C.; MacDonald, J. C.; Bernstein, J. Acta Crystallogr. 1990, B46, 256−262. (65) Bernstein, J.; Davis, R. E.; Shimoni, L.; Chang, N.-L. Angew. Chem., Int. Ed. Engl. 1995, 34, 1555−1573. (66) Starbuck, J.; Norman, N. C.; Orpen, A. G. New J. Chem. 1999, 23, 969−972. (67) Bryant, R.; James, S. C.; Norman, N. C.; Orpen, A. G. Acta Crystallogr. 1998, C54, 1113−1115. (68) Nyburg, S. C.; Faerman, C. H. Acta Crytallogr. 1985, B41, 274− 279. (69) Homesland, O.; Romming, C. Acta Chem. Scand. 1966, 20, 2601−2610. (70) Bjorvatten, T. Acta Chem. Scand. 1963, 17, 2292−2300. (71) Steiner, T. New J. Chem. 2000, 24, 137−142. (72) In spite of the partial occupancy of the cavities, the crystalline order of the complex was well maintained. (73) Dance, I.; Scudder, M. J. Chem. Soc., Dalton Trans. 1996, 3755− 3769. (74) Dance, I.; Scudder, M. J. Chem. Soc., Dalton Trans. 1998, 3167− 3175. (75) Lorenzo, S.; Horn, C.; Craig, D.; Scudder, M.; Dance, I. Inorg. Chem. 2000, 39, 401−405. (76) Cambridge Structural Database (Version 5.32, August 2011 update): Allen, F. H. Acta Crystallogr. 2002, B58, 380 Surveys were based on a VDW radii cut-off for ordered structures determined from single crystal X-ray analysis (no powder), with 3-D coordinates determined, crystallographic residual R < 0.1, and any nonmetal atom bonded to three phenyl rings (-C6H5) and any group VI or VII atom other than oxygen). (77) Refcodes: ADOLUA, BAQTOC, BARNUD, BRTPSN, FEGRAK, HOTTAL, LUHQIO, NOFKOI, OCALOT, PAQKAT, QUQCUA, SIBJOC, SIDSAA, TPASNS, TPGEBR, TPPHSE, TPPHSE01, TPPOSS04, TPPOSS09, TPSNCL02, UMEWOZ, WAKHOF, WEHZEO02, XIZBIS, ZZZHUE01, ZZZJMS11. (78) Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. Rev. 1988, 88, 899−926. (79) Wiberg, K. B. Tetrahedron 1968, 24, 1083−1096.

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Complementary SeleniumÂ·Â·Â·Iodine Halogen Bonding and Phenyl

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