Statistics-Based Design of Multicomponent Molecular Crystals with the

Feb 20, 2009 - These results were utilized to prepare six multicomponent crystals that exploit the three-center hydrogen bond mainly through the R4. 2...
1 downloads 0 Views 2MB Size
Download PDF
Statistics-Based Design of Multicomponent Molecular Crystals with the Three-Center Hydrogen Bond Sagi Eppel and Joel Bernstein* Department of Chemistry, Ben-Gurion UniVersity of the NegeV, P.O Box 653, Be′er SheVa 84105, Israel

CRYSTAL GROWTH & DESIGN 2009 VOL. 9, NO. 4 1683–1691

ReceiVed March 17, 2008; ReVised Manuscript ReceiVed January 11, 2009

ABSTRACT: A statistical survey was carried out to determine the probability for combinations of specific CO and NH groups to form a three-center hydrogen bond between one CO and two NH groups. The results show significantly higher probabilities for charged CO- groups. These results were utilized to prepare six multicomponent crystals that exploit the three-center hydrogen bond mainly through the R42(8) motif. 1. Introduction The use of hydrogen bond motifs (synthons) as a structure guiding interaction for crystal engineering1–3 as well as other forms of molecular self-assembly4,5 has been developing rapidly in the past few years. Although the ability to accurately predict crystal structures of molecules is still limited,6 some synthons that involve strong hydrogen bonds could be expected with high probability to be formed when the appropriate functional groups are used.7 In this work, we have focused on utilization of the three-center hydrogen bond between one CO and two NH groups (1, Figure 1) for crystal engineering with specific emphasis on the R42(8) motif8,9 (motif 2, Figure 1) which is the main ring motif that utilizes this interaction (Hydrogen bond motifs are given by graph set notation:8–10 Gad(n) where G is the motif type (e.g., R (ring), C (infinite chain)), n is the number of atoms in the motif, a the number of hydrogen bond acceptors, and d the number of hydrogen bond donors). Utilization of the R24(8) motif 2 can allow formation of the three-center hydrogen bond 1 in a geometrically predictable way and hence might open the way for design of multi component crystals with predictable structures using this interaction, similar to the way the standard twocenter hydrogen bond (D-H · · · A) has been utilized in hydrogenbond ring motifs (synthons) to design crystals with predictable motifs (e.g., the R22(8) ring motif).1,11–13 In the work reported here, a systematic survey was carried out on the Cambridge Structural Database (CSD)14 in order to determine the probability for every combination of specific donor and acceptor groups (restricted to CO and NH groups15) to form the threecenter hydrogen bond 1. The results show that charged COgroups exhibit significantly higher probability to form the three center hydrogen bond. The results of the statistical survey were demonstrated by preparing six molecular crystals with motifs that exploit the three-center hydrogen bond 1 mainly through the R42(8) ring motif 2. 2. Survey of the Cambridge Structural Database (CSD) The survey of the CSD was carried out to evaluate the probability of forming the three-center hydrogen bond 1 (Figure 1), and the R42(8) motif 2 (Figure 1) by a combination of a specific donor and acceptor. The results in percentage are given in Tables 2 and 3 for the three-center hydrogen bond 1 (Figure 1), and the R42(8) motif 2, respectively. * Corresponding author. Phone: 972-8-646-1187; 972-8-646-9519. Fax: 9728-647-7641. E-mail: [email protected]. Web: http://www.bgu.ac.il/chem/eng/ personal/bernstein.html.

Figure 1. Motifs 1-4. Dashed lines represent hydrogen bonds.

Figure 2. R22(8)R24(8) motifs 5 and 6.

2.1. Statistical Methods. The complete probability for a combination of specific donor and acceptor in a structure to form a specific motif (Pf) can be written as Pf ) PmPH, where PH is the probability for a specific donor and acceptor combination to form a hydrogen bond between them and Pm is the probability of the hydrogen bond formed between the specific donor and acceptor will take part in the motif. Now PH, the general probability for hydrogen-bond formation, has already been widely explored,16 and not specifically dependent on the motif. Clearly claiming that COO- and NH3+ combination have higher probability to form a specific motif will have little meaning, if it was only based on the fact that these groups simply have higher probability to form a hydrogen bond between them. That leaves Pm as the only probability that is specifically relevant to the motif formation and therefore the only statistic that is relevant to our work. For this reason, we will use the probability Pm as the main tool in the statistical part of this work. However, it is important to remember that Pm is not identical to Pf, but only proportional to it. Therefore, Pm values will be considered only relative to other Pm values. 2.2. Definition of Probabilities P1 and P2. To evaluate the probability that the combination between specific CO and NH groups will form the three-center hydrogen bond 1 (Figure 1), we define P1 (Table 2) as the probability that a hydrogen bond between specific CO and NH groups will take part in the threecenter hydrogen bond 1. P1 is given by

10.1021/cg8002788 CCC: $40.75  2009 American Chemical Society Published on Web 02/20/2009

29473 11971 612 14353 695 6252 1572 455 231 602 895 267 322 298 934 1536 934 1958 962

NH any C2NH0 C3NH+ NH2 any NH4+ CNH3+ C2NH2+ CdNH2+ N+CCNH2 N+dC(N)NH2 X+dC-NH2 (X)C,N) ArNH3+ C0N0CNH20 N02CNH20 X0dC-NH2 (X)C,N) CCONH2 Ar-NH20 H-N-C-NH2 H-NdC-NH2

455 33 51 260 17 106 83 9 9 9 19 17 0 3 4 3 4 25 23

Ar-O 761 61 57 460 33 181 112 25 19 36 58 23 4 4 22 8 22 70 57

X2CO- (X)C,N) 666 46 55 407 29 153 105 20 16 30 50 23 3 4 18 8 18 66 54

C2CO9746 641 437 7862 453 4896 1174 306 159 426 641 132 21 19 340 64 340 768 703

COO7841 6574 13 994 29 196 38 27 9 29 38 0 90 144 152 154 152 155 41

(CN)CC)O0 1599 1241 1 305 13 19 7 14 22 14 36 2 114 32 38 13 38 69 36

(CN)2CdO0 1297 103 0 1182 9 49 3 0 1 0 1 0 2 6 8 1075 8 18 2

CCONH2 1965 435 33 1353 88 628 126 28 7 57 65 69 31 55 154 123 154 163 67

COOH 1311 673 13 463 34 64 43 17 10 23 33 11 8 3 89 26 89 64 36

C2CdO0

Table 1. Ntot, the Number of Hydrogen Bonds between Specific NH and CO Groups in the CSD 13727 8751 30 3841 103 360 92 68 43 73 116 13 220 192 312 1349 312 899 124

X2CdO0 (X)C,N) 2433 1763 4 479 0 83 23 9 1 4 5 17 22 16 62 57 62 29 3

C-O-CdO

6462 5729 7 622 22 160 25 9 6 16 22 0 42 112 123 105 123 104 23

C(NH)CdO

CO any

37 16 5 58 80 64 36 71 37 46 70 82 47 54 54 78 54

P1 %

NH any C2NH0 C3NH+ NH2 any NH4+ CNH3+ C2NH2+ CdNH2+ C0N0CNH20 N02CNH20 N+CCNH2 N+dC(N)-NH2 CCONH2 C(SP2)-NH20 Ar-NH20 X+dC-NH2 (X)C, N) X0dC-NH2 (X)C, N)

〈100〉 〈56〉 〈100〉 〈33〉 (78) 〈100〉 〈79〉 〈100〉

48 (45) 2 67 〈88〉 75 42 〈78〉

Ar-O53 46 4 70 (88) 76 47 (72) 〈100〉 〈100〉 〈63〉 (92) 〈38〉 74 (73) 83 (73)

X2CO- (X)C, N) 50 46 2 68 (90) 73 44 〈70〉 〈100〉 〈100〉 〈56〉 (97) 〈38〉 75 〈72〉 82 〈72〉

C2CO69 65 10 79 89 85 53 83 (81) 〈74〉 90 89 88 84 84 89 84

COO12 10 〈15〉 28 (66) 13 (13) (11) 30 39 〈11〉 (48) 18 30 36 (39) 36

(CN)CCdO0 37 36 〈0〉 42 〈54〉 〈26〉 〈57〉 〈64〉 28 (72) (36) 〈64〉 〈31〉 39 (45) (47) (45)

(CN)2CdO0

53 54 〈100〉 〈100〉 〈100〉

〈100〉 〈100〉

54 〈67〉 37 〈33〉

53 48

CCONH2

25 11 (0) 32 81 20 5 (64) (48) 31 〈0〉 68 26 45 35 60 35

COOH

19 10 〈0〉 35 (59) 36 (44) 〈82〉 〈38〉 〈33〉 〈60〉 (100) (12) 27 29 (88) 29

C2CdO0

25 15 (7) 49 68 25 32 46 30 48 (37) 66 48 51 39 55 39

X2CdO0 (X)C, N)

10 (9) 〈33〉 (23) 〈6〉 〈0〉 〈50〉 5 17 27 〈40〉 27

6 4 〈0〉 16

C-O-CdO

12 10 〈14〉 29 (64) 12 (20) 〈11〉 (31) 38 〈0〉 〈44〉 23 33 38 (32) 38

C(CHN)CdO

Table 2. P1 Probability in Percentage for a Hydrogen Bond between CO and NH Groups to Participate in the Three-Center Hydrogen Bond 1; Cases of 20 < Ntot < 45 Appear As (P), Cases of Ntot < 20 Appear As 〈P〉; Only Cases with Ntot > 20 Should Be Considered As Statistically Significant

CO any

Ntot

-

1684 Crystal Growth & Design, Vol. 9, No. 4, 2009 Eppel and Bernstein

2 (9) 〈0〉 〈0〉 〈0〉 〈0〉 〈0〉 (18) 〈0〉 23 0 23 (0) 〈0〉

(29) 18 21 4 21 2 (0)

10 (18) 8 (0) 〈0〉 〈0〉 〈0〉 (0)

〈0〉 〈33〉 〈25〉 19 25〉 〈0〉 〈0〉

〈0〉

〈0〉

24 14 20 3 20 1 (0)

C(NH)CdO C-O-CdO

9

14 30 13 13 9 (9) 11 10 〈38〉 15 14 11 15 11 15 10 12 (21) 27 (28) 〈24〉 〈0〉 (26) (18) 〈45〉 〈0〉 〈0〉 0 (0) 0 9 (17) 18 74 13 3 (39) 〈0〉 35 31 36 (0) 13 7 10 7 24 31 19 〈33〉 27 〈0〉

11 〈15〉 〈0〉 〈0〉 〈0〉 (18) 〈14〉 (17) 〈0〉 12 (19) (0) 〈0〉 (0) 20 (17) 8 (21) 6 (0) (0) 〈0〉 (0) (0)

32 56 38 12 17 28 24 25 62 (0) 〈11〉 27 19 27 24 28

P1 )

N1 Ntot

Where Ntot is the total number of symmetry-independent hydrogen bonds between the specific CO and NH groups in the CSD (Table 1), and N1 is the number of symmetry independent hydrogen bonds between the specific CO and NH groups that participate in the three-center hydrogen bond 1. And similarly, to evaluate the probability that a combination between specific CO and NH groups will form the R24(8) motif 2 (Figure 1), we determined P2 as

P2 )

N2 Ntot

Where N2 is the number of symmetry-independent hydrogen bonds between the specific CO and NH groups that are part of the R42(8) motif 2. Hydrogen bonds were chosen as the population for the statistics for two main reasons: (1) Because the formation of hydrogen bonds between two groups can be designed with high precision,12,13,17 this method allows a potentially efficient way to design crystals that utilize this motif. (2) Focusing on hydrogen bonds as the population for the statistics reduces the weight of other factors that are not directly relevant for this study. Among these is the probability for formation of a single hydrogen bond, which is already wellstudied,16 and which depends on properties such as the existence of competing donors and acceptors in the crystal, factors that cannot be evaluated within this statistic. 2.3. Data Retrieval Methods. All searches were carried out on the CSD April 2007 release using Conquest18 version 1.9. The hydrogen-bond cutoff distance was the sum of the atoms van der Waals radii, and the hydrogen bond angle was limited to 90° < N-H · · · O < 180°. For charged groups, the CO and C-N bonds were defined as double, single, or delocalized and the O atom was defined to be covalently bonded to only one neighbor. These criteria were chosen because in many cases there is not a clear distinction between C-O- and CdO or C-NH2+ and CdNH2.7 The location of the hydrogen atoms was normalized to standard distance values.7 The database was limited to structures of only organic molecules with R < 0.10 not disordered and containing no errors. All the symmetryindependent instances of motifs 1, 2 (Figure 1) and the CO · · · HN hydrogen bond (for Ntot) in the CSD, and all the symmetry-independent instances of specific NH and CO groups in the CSD, were found once with the Conquest software. All the statistics were then obtained by a program we wrote to combine these results to determine N1, N2, and Ntot for each combination of CO and NH groups. The results of Ntot for several functional groups are summarized in Tables 1-3.

〈0〉 〈0〉 〈0〉 〈0〉 (0) (0)

30 (58) 39 29 (16) 〈0〉 (28) 21 (48) 〈0〉 〈0〉 (0) 〈0〉 (0) 11 14 24 〈47〉 31 24 〈0〉 〈0〉 〈0〉 〈0〉 〈35〉

27 (59) 34 28 (0) 〈0〉 (20) 16 (48) 〈0〉 〈0〉 〈0〉 〈0〉 〈0〉 12 15

X2CdO0 (X)C,N) C2CdO COOH CCONH2 (CN)2CdO0 (CN)CCdO0 COOC2COX2CO- (X)C,N) Ar-O-

Crystal Growth & Design, Vol. 9, No. 4, 2009 1685

CO any

21 45 26 10 13 20 19 20 31 13 13 16 15 16 16 19 NH2 any NH4+ CNH3+ C2NH2+ CdNH2+ N+CCNH2 N+dC(N)NH2 X+dC-NH2 (X)C,N) ArNH3+ C0N0CNH20 N02CNH20 X0dC-NH2 (X)C,N) CCONH2 Ar-NH20 H-N-C-NH2 H-NdC-NH2

3. Statistical Results

P2 %

Table 3. P2 Probability in Percentage for a Hydrogen Bond between CO and NH Groups to Participate in the R24(8) Motif 2; Cases of 20 < Ntot < 45 Appear As (P), Cases of Ntot < 20 Appear as 〈P〉, Where P is the Probability in Percentage; Only Cases with Ntot > 20 Should Be Considered As Statistically Significant

Statistics-Based Design of Crystals with a Three-Center H-Bond

3.1. P1 Probability for Formation of a Three-Center Hydrogen Bond between CO and Two NH Groups. From Table 2 it can be seen that the probability P1 to form the three center hydrogen bond 1 for charged CO- groups is much higher than for neutral CdO groups. This is true for combinations with neutral as well as charged NH groups. It is interesting to note the similarity between 1 and the NH bifurcated bond with two CO acceptors (3, Figure 1), which also have a higher probability to form for charged NH+ groups.19 This suggests that the formation of this three-center hydrogen bond is largely due to ionic interactions.20–24 Also steric hindrance probably plays

1686 Crystal Growth & Design, Vol. 9, No. 4, 2009

Eppel and Bernstein

Figure 3. (a) R24(8) motif 2 with the atoms numbered. (b) Plane formed by atoms H1H2H3. (c) Plane formed by atoms N1H2H1. (d) Plane formed by atoms O1H1H3. (e) Histogram of the angle between planes H1N1H3 and H1H2H3 in the R24(8) motif 2. (f) Histogram of angle between planes H1O1H3 and H1H2H3 in the R24(8) motif 2. Note that under inversion symmetry (which corresponds to majority of the cases), these two angles almost completely define the R24(8) motif geometry.

some role as can be seen from the low P1 values for C3NH+ compared to C2NH0, and the low P1 value for C2NH2+ compared to other charged CNH2+ groups. The COO- group has the highest P1 values,19 and mostly (51%) form the three-center hydrogen bond with the R12(4) motif (4, Figure 1). 3.2. P2 Probability for Formation of the R42(8) Motif 2. From Table 3 it can be seen that charged CO- and NH2+ groups generally have the highest probability (P2) to form R24(8) motif 2, with the highest P2 values for NH groups of CNH3+ and NH4+ mainly when combined with charged CO- groups. Also, combinations of NH and CO groups that can form motifs with combined R22(8)R42(8) graph set (motifs 5 and 6 in Figure 2) have higher P2 values (17% 2σ(I)] final R1 on observed data final wR2 on observed data crystal habit

I

C3H7N6+ C7N2O6H3-C7N2O6H4 550.38 P21/c 7.172(2) 10.441(3) 30.461(9) 90 103.423(8) 90 2218.7(1) 4 293 (2) 1.648 1128 5192 1391 0.0712 0.1545 needle

III NH4+ C7NO4H4184.15 P1j 7.038 (2) 7.596 (2) 15.973 (5) 85.866(6) 82.325(7) 81.876(7) 836.6 (4) 4 297 (2) 1.462 384 3720 1651 0.0492 0.108 needle

II C6ONH14+ C7N2O6H3326.29 P21/c 5.920 (2) 18.024 (7) 15.512 (6) 90 91.853 (8) 90 1654.2 (1) 4 296 (2) 1.31 684 3727 1249 0.0488 0.1112 needle

IV (C6BrNH7+)2 C10O8H4-2 299.1 I2/m 3.8623 (2) 9.206 (4) 30.164 (1) 90 92.688 (7) 90 1071.3 (7) 4 298 (2) 1.854 596 1315 1118 0.0774 0.2268 tabular

Table 6. Crystallographic Information on Structures I-VI V C6BrNH7+ C9O6H5400.18 P21/c 3.9071 (1) 32.109 (8) 12.733 (3) 90 96.277 (5) 90 1587.8 (7) 4 298 (2) 1.674 808 3661 2363 0.0416 0.1085 needle

VI C3H7N6+ C3O4H3230.2 P1j 5.2073 (2) 7.511 (2) 13.112 (4) 100.320 (6) 98.075 (6) 106.344 (6) 474.2 (3) 2 298 (2) 1.612 240 2099 1551 0.0456 0.1304 prismatic

1688 Crystal Growth & Design, Vol. 9, No. 4, 2009 Eppel and Bernstein

Figure 5. Some of the hydrogen bond motifs appearing in structures I-VI.

Figure 6. Structure I, the R22(8)R24(8) motif 6 (Figure 2).

ratio), and the solution was then left for a few days at room temperature for slow evaporation of the solvent, when tabular colorless crystals formed. (e) 1,3,5-Benzenetricarboxylic Acid 4-Bromoaniline. 4-Bromoaniline and 1,3,5-benzenetricarboxylic acid in molar ratio of 1:1 were

Statistics-Based Design of Crystals with a Three-Center H-Bond

Crystal Growth & Design, Vol. 9, No. 4, 2009 1689

Figure 7. Structure II: (a) R24(8)R44(12) ribbon motif 5 (Figure 5); some of the methyl groups have been deleted for clarity. (b) Unit cell.

Figure 8. Structure III: (a) R24(8)R21(4)C12(4) motifs 7 and 11 (Figure 5b). (b) Hydrogen bonds sheet with the R24(8)R42(8) Motif 2.

Figure 9. Structure IV: (a) unit-cell composed of charged/neutral layers; (b) R23(6)C12(4) motif 10. dissolved in a mixture of water and acetone (about 1:3 ratio), and the solution then left for a few days for slow evaporation of the solvent when colorless needle crystals appeared.

(f) 1,3,5-Triamino-2,4,6-triazine with Malonic Acid. 1,3,5-triamino-2,4,6-triazine and malonic acid in a molar ratio of 1:1 were gradually added to water (heated to about 80°) until the solution reached

1690 Crystal Growth & Design, Vol. 9, No. 4, 2009

Figure 10. Square charge arrangement in the R24(8) and R23(6) motifs 1 and 9 with charged NH2+ and CO- groups.

Eppel and Bernstein

Figure 11. Structure V: (a) R23(6)C12(4) and R24(8) motifs; (b) unit cell.

saturation and sediment appeared (later identified as powder of VI). The sediment was then filtered, and the solution was left to cool to room temperature for a few hours when prismatic colorless crystals formed. 4.3. Structure Solution and Refinement. Single-crystal crystallographic data were collected on a Bruker SMART 1000K diffractometer using Mo KR radiation (λ ) 0.71073 Å) with a graphite monochromator. The data were reduced by SAINT30 solved with SHELXS31 and then refined with SHELXL.31 All hydrogens were found directly from the electron density difference map. See Table 6. 4.4. Crystal Structure of Multicomponent Crystals. (a) 1,3,5-Triamino-2,4,6-triazine and 3,5-Dinitrobenzoic Acid. 1,3,5Triamino-2,4,6-triazine crystallized with 3,5-dinitrobenzoic acid in a 1:2 ratio and exhibits a flat ribbon structure with the R24(8) motif 2 present as part of a R22(8)R24(8) motif 6 (Figures 2 and 6). The R22(8)R24(8) motif (Figure 6) has an almost completely planar geometry (5.4 degrees between the R24(8) and the R22(8) planes), which mainly results from the combination between the motif inversion symmetry and the planar structure of the 1,3,5-triamino-2,4,6-triazine. (b) 3,5-Dinitrobenzoic Acid with Diacetoneamine. The R24(8) motif 2 is present as part of parallel ribbons (Figure 7a) with R22(8)R44(12) motif 9 (Figure 5) with an angle of 60° between the plane of the R24(8) motif 2 and the approximate plane of the R44(12) motif 12. Again, the R24(8) and R44(12) motifs (12 and 2 in Figure 5) lie on crystallographic inversion centers. The interaction between the ribbons of the R22(8)R44(12) motif is based mainly on NO · · · H-C hydrogen bonds (Figure 7b). (c) Ammonia and 3-Nitrobenzoic Acid. The crystal structure of the salt of ammonia and 3-nitrobenzoic acid (ammonium salt of 3-nitrobenzoic acid) is composed of neutral layers (Figure 8a) of aromatic rings and ionic layers of charged O- and NH4+ in which the R24(8) motif 2 appears to be the dominant hydrogen-bond interaction. Figure 8b shows some of the chain motifs that form in the ionic layer. As a result the ionic packing of the O- and NH4+ groups (Figure 10) and the ability of the NH4+ to participate in a large number of hydrogen bonds, the R24(8) motif 2 is the main hydrogen bond interaction in the crystal. (d) 4-Bromoaniline and 1,2,45-Benzenetetracarboxylic Acid. The structure (Figure 9a) consists of alternating ionic and neutral layers. The ionic layers are based on the R23(6)C12(4) motif 10 (Figure 9b). The linear geometry of the motif is a result of the mirror plane at its center and the translation symmetry between the R23(6) motifs (Figure 9b). Note that the R23(6) motif 9 contains O- and N+ ions oriented in a manner similar to that of the R24(8) motif 2 (Figure 10). (e) Monohydrate crystal of 1,3,5-Benzenetricarboxylic and 4-Bromoaniline. Only one of the 1,3,5 benzenetricarboxylic three carboxylic groups loses a proton (Figure 11b). The R23(6)C12(4) motif appears perpendicular to the plane of the 1,3,5 benzenetricarboxylic ring (Figure 11a), but in this case instead of two CO- acceptors in synthon 10 (structure IV Figure 9b) the second acceptor is the oxygen of a water molecule. The R24(8) motif with the water oxygen as acceptor also appears; however, it less dominant (higher angle and distance) than the R23(6) motif (Figure 11a). (f) 1,3,5-Triamino-2,4,6-triazine with Malonic Acid. The structure is composed of hydrogen-bonded sheets (Figure 12) with a 1:1 ratio of 1,3,5-triamino-2,4,6-triazine and malonic acid. The three-center hydrogen bond 1 appears as part of R23(8) motif (Figure 12). Again, the planar geometry of the hydrogen-bond sheets can be attributed to

Figure 12. Structure VI showing the hydrogen-bond sheet structure. the combination between the inversion symmetry and the planar structure of the 1,3,5-triamino-2,4,6-triazine molecule and the R22(8) motif.

5. Discussion The appearance of the three center hydrogen bond 1 in all the crystal structures that were solved supports the statistical results regarding the high probability of charged CO- groups to form this interaction. Furthermore, the results suggest that the three-center hydrogen bond can be designed with a good probability to form specific motifs such as the R42(8) ring motif 2 in structures I, II and III. The high probability of charged CO- groups to form the three-center hydrogen bond 1 is also noteworthy considering the growing interest in the chargeassisted hydrogen bond23 as tool for crystal engineering and self-assembly. From Table 2, it can be seen that the three-center hydrogen bond is the most common interaction for many charged CO- groups and therefore can be a major tool in the utilization of charge-assisted hydrogen bonds22,23 for crystal engineering. The high probability of the three-center hydrogen bond to form as part of the R42(8) ring motif might be explained by the fact that this motif appears to best utilize the square charge arrangement (Figure 10), which is a common ionic arrangements for organic and inorganic crystals. It can be seen from the experimental and the statistical results, that motif 2 tends to appear as part of larger hydrogen-bonds motifs. Utilization of these larger motifs, such as the R22(8)R42(8) motif in structure I might provide a useful tool for increasing the

Statistics-Based Design of Crystals with a Three-Center H-Bond

Crystal Growth & Design, Vol. 9, No. 4, 2009 1691

control over both the motif formation probability (section 3.2) and its structural rigidity (structure I).

(7) Allen, F. H.; Motherwell, W. D. S.; Raithby, P. R.; Shields, G. P.; Taylor, R. New J. Chem. 1999, 23, 25–34. (8) Etter, M. C. Acc. Chem. Res. 1990, 23, 120–126. (9) Etter, M. C.; Macdonald, J. C.; Bernstein, J. Acta Crystallogr., Sect. B 1990, 46, 256–262. (10) Bernstein, J.; Davis, R. E.; Shimoni, L.; Chang, N.-L. Angew. Chem., Int. Ed. 1995, 34, 19. (11) Aakeroy, C. B. Acta Crystallogr., Sect. B 1997, 53, 569–586. (12) Etter, M. C. J. Phys. Chem. 1991, 95, 4601–4610. (13) Steiner, T. Angew. Chem., Int. Ed. 2002, 41, 48–76. (14) Allen, F. H. Acta Crystallogr., Sect. B 2002, 58, 380–388. (15) Pirard, B.; Baudoux, G.; Durant, F. Acta Crystallogr., Sect. B 1995, 51, 103–107. (16) Mills, J. E. J.; Dean, P. M. J. Comput.-Aided Mol. Des. 1996, 10, 607–622. (17) Infantes, L.; Motherwell, W. D. S. Z. Kristallogr. 2005, 220, 333– 339. (18) Bruno, I. J.; Cole, J. C.; Edgington, P. R.; Kessler, M.; Macrae, C. F.; McCabe, P.; Pearson, J.; Taylor, R. Acta Crystallogr., Sect. B 2002, 58, 389–397. (19) Taylor, R.; Kennard, O.; Versichel, W. J. Am. Chem. Soc. 1984, 106, 244–248. (20) Felix, O.; Hosseini, M. W.; De Cian, A.; Fischer, J. New J. Chem. 1998, 22, 1389–1393. (21) Fagan, P. J.; Ward, M. D. PerspectiVes in Supramolecular Chemistry: The Crystal as a Supramolecular Entity; Wiley-Interscience: Malden, MA, 1996; Vol. 2, pp 107-135. (22) Meot-Ner, M. Chem. ReV. 2005, 105, 213–284. (23) Ward, M. D. Chem. Commun. 2005, 5838–5842. (24) Szatylowicz, H.; Krygowski, T. M. J. Mol. Struct. 2007, 844, 200– 207. (25) Eppel, S.; Bernstein, J. Acta Crystallogr., Sect. B 2008, 64, 50–56. (26) Macchiarulo, A.; Pellicciari, R. J. Mol. Graph. 2007, 26, 728–739. (27) Glusker, J. P. In Structure-Based Drug Design Conference; Panama City Beach, FL, April 22-25, 1994; Cambridge Healthtech Institue: Needham, MA, 1994; p 418-427. (28) Bradbury, R. B.; Hancox, N. C.; Hatt, H. H. J. Chem. Soc. 1947, 1394–9. (29) Vicente, J.; Chicote, M. T.; Guerrero, R.; Vicente-Hernandez, I.; Jones, P. G. Inorg. Chem. 2003, 42, 7644–7651. (30) SAINT, 6.22 ed.; Bruker Analytical Systems: Madison, WI, 19972001. (31) Sheldrick, G. M. SHELXS and SHELXLUniversity of Go¨ttingen: Go¨ttingen, Germany, 1997.

6. Conclusion A statistical survey was carried out to determine the probability of CO and NH groups to form a three-center hydrogen bond between one CO and two NH groups 1 (Figure 1). The results of this survey show that charged CO- groups have a significantly higher probability to form this interaction. The R42(8) motif 2 is the most common ring motif that utilizes the three-center hydrogen bond and appears mainly through the R22(8)R24(8) motif or in a combination of CNH3+ NH4+ with COgroups in which it utilizes the square ionic arrangement common in ionic structures. Acknowledgment. This work was supported by a grant from the US-Israel Binational Science Foundation (BSF) Jerusalem under Grant 2004118. Supporting Information Available: Crystallgraphic information in CIF format. This material is available free of charge via the Internet at http://pubs.acs.org.

References (1) Desiraju, G. R. Angew. Chem., Int. Ed. 1995, 34, 2311–2327. (2) Garciatellado, F.; Geib, S. J.; Goswami, S.; Hamilton, A. D. J. Am. Chem. Soc. 1991, 113, 9265–9269. (3) Hofmann, D. W. M.; Kuleshova, L. N.; Antipin, M. Y. Cryst. Growth Des. 2004, 4, 1395–1402. (4) Melendez, R. E.; Carr, A. J.; Linton, B. R.; Hamilton, A. D. In Molecular Self-Assembly; Springer-Verlag: Berlin, 2000; Vol. 96, p 31-61. (5) Krische, M. J.; Lehn, J. M. In Molecular Self-Assembly; SpringerVerlag: Berlin, 2000; Vol. 96, p 3-29. (6) Day, G. M.; Motherwell, W. D. S.; Ammon, H. L.; Boerrigter, S. X. M.; Della Valle, R. G.; Venuti, E.; Dzyabchenko, A.; Dunitz, J. D.; Schweizer, B.; van Eijck, B. P.; Erk, P.; Facelli, J. C.; Bazterra, V. E.; Ferraro, M. B.; Hofmann, D. W. M.; Leusen, F. J. J.; Liang, C.; Pantelides, C. C.; Karamertzanis, P. G.; Price, S. L.; Lewis, T. C.; Nowell, H.; Torrisi, A.; Scheraga, H. A.; Arnautova, Y. A.; Schmidt, M. U.; Verwer, P. Acta Crystallogr., Sect. B 2005, 61, 511–527.

CG8002788