Article pubs.acs.org/crystal
Supramolecular Polymers with [Co(en)3]3+ Cores (en = ethylenediamine) Thomas J. Liebig and Uwe Ruschewitz* Department of Chemistry, University of Cologne, Greinstraße 6, D-50939 Cologne, Germany S Supporting Information *
ABSTRACT: From aqueous solutions containing Λ-[Co(en)3]I3 (1, 2), Δ-[Co(en)3]I3 (5), or racemic [Co(en)3]I3 (3, 4) AgI and PbI2 respectively were precipitated by addition of Ag2EDC, [Ag(en)][Ag(BDC)], PbADC or (NH4)[Ag5(BTC)2(NH3)(H2O)2] and filtered off (en = ethylenediamine, H2EDC = fumaric acid, H2BDC = terephthalic acid, H2ADC = acetylenedicarboxylic acid, H3BTC = trimesic acid). After slow evaporation of the remaining solutions single crystals of 1∞{Λ-[Co(en)3]EDC3/2}·5.625H2O (P21, Z = 4, 1), 1∞{Λ-[Co(en)3]BDC3/2}·10H2O (P1, Z = 2, 2), 2 2 ∞{[Co(en)3]ADC3/2}·4H2O (P1̅, Z = 2, 3), ∞{[Co(en)3]BTC}·5.55H2O (P21/c, Z = 8, 4), and 2∞{Δ-[Co(en)3]EDC(NO3)}·2H2O (C2, Z = 4, 5) were obtained. In all compounds the [Co(en)3]3+ cores are connected in a T-shaped mode via N−H···O hydrogen bonds to the carboxylates to form complex networks. Water molecules are bound via O−H···O hydrogen bonds to the networks, further increasing their complexity. It is noteworthy that the chirality of the starting material (Λ- or Δ[Co(en)3]I3) is maintained during the reaction thus leading to non-centrosymmetric polymers, whereas with racemic [Co(en)3]I3 centrosymmetric polymers are obtained.
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the polymeric network.23 In our first attempts we have concentrated on the well-known complex [Co(en)3]3+,24 as the separation of chiral Λ- or Δ-[Co(en)3]3+ from the racemic mixture is well established.25 In 2011 Zhi-Sheng et al. reported four pillared-layer type supramolecular networks based on [Co(en)3]3+ and 2,6-naphthalenedicarboxylate or 4,4-biphenyldicarboxylate as linking anions.26 But as racemic [Co(en)3]3+ was used as the starting material only compounds crystallizing in centrosymmetric space groups were obtained. Here we present five new supramolecular polymers based on racemic [Co(en)3]3+ and chiral Λ- or Δ-[Co(en)3]3+, respectively. During the synthesis the chirality of the starting material is preserved, so that the latter lead to NCS compounds.
INTRODUCTION The number of publications in the field of supramolecular polymers and coordination polymers, in particular, metal− organic frameworks and their porous derivatives, has increased exponentially in the past decade. This is mainly due to numerous possible applications that have been predicted for these compounds, e.g., gas storage and separation, drug release, catalysis, and sensors to name a few.1−4 But also the structural variability of supramolecular and coordination polymers, which in a simple picture can be assembled from molecular building blocks,4−6 has attracted many chemists working in this field. In this respect it has also been attempted to synthesize noncentrosymmetric (NCS) polymers in a directed approach due to their importance as second-order nonlinear optic (NLO) materials.7−9 But the rational design, i.e., the development of strategies toward the controlled synthesis of NCS solids, is still a challenging task, although several promising examples based on diamondoid networks,10−14 helical chains,15 or bananashaped ligands16 have been reported. It was also found that stereochemically active lone pairs 17−20 or coordination polymers containing linear and trigonal planar anions21 enhance the probability of obtaining NCS compounds. But probably still the most successful approach is the incorporation of chiral building blocks into supramolecular and coordination networks.22 In the past this approach has been mainly restricted to the organic (anionic) part of the networks, as chiral carboxylic or amino acids are cheaply available from nature’s chiral pool. In a brief contribution we showed that also chiral (inorganic) complexes can be used to construct NCS supramolecular polymers, where they constitute the nodes of © 2012 American Chemical Society
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EXPERIMENTAL SECTION
Synthesis. Racemic [Co(en)3]I3 and chiral Λ- or Δ-[Co(en)3]I325 as well as Ag2EDC,27 [Ag(en)][Ag(BDC)],28 PbADC,29 and (NH4)[Ag5(BTC)2(NH3)(H2O)2]30 were prepared according to the procedures described in the literature (en = ethylenediamine, H2EDC = fumaric acid, H2BDC = terephthalic acid, H2ADC = acetylenedicarboxylic acid, H3BTC = trimesic acid). In general, AgI or PbI2 was precipitated from aqueous solutions containing Λ-, Δ- or racemic [Co(en)3]I3 and a silver or lead salt of the respective linker ligand. After filtration single crystals of 1−5 were obtained after slow evaporation of the remaining solutions. All compounds were unstable due to an easy loss of solvent water molecules. Accordingly, single crystal structure analysis was carried out Received: July 19, 2012 Revised: September 5, 2012 Published: September 24, 2012 5402
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X-ray Single Crystal Structure Analysis. All isolated crystals showed differing sensitivity to dehydration after leaving their mother liquor. Single crystals of 3 are the most stable ones. They were isolated and transferred into a glass capillary, which was sealed thereafter. The measurement was carried out on a STOE IPDS I single crystal diffractometer (Mo−Kα radiation) at room temperature. Single crystals of 1, 2, 4, and 5 were isolated from a perfluorinated oil, transferred into a drop of a highly viscous oil, fixed in a loop (ϕ = 1 mm), and immediately mounted on the diffractometer. 1 and 4 were measured on a STOE IPDS II single crystal diffractometer (Mo−Kα radiation) and 3 on a STOE IPDS 2T single crystal diffractometer (Mo−Kα radiation), all in a 170 K nitrogen stream. A single crystal of 5 was measured on a NONIUS KAPPA CCD single crystal diffractometer (Mo−Kα radiation) at 100 K. For data collection and reduction of crystals measured on the STOE diffractometers the STOE program package31 was applied. Data collected on the NONIUS KAPPA CCD were treated with COLLECT32 for data collection and DENZO33 for data reduction. The structural models were solved using SIR200434 and completed using difference Fourier maps calculated with SHELXL-97,35 which was also used for final refinements. These programs were run under the WinGX 1.80.05 system.36 All non-hydrogen atoms with the exception of some oxygen atoms of water molecules (details see below) were refined anisotropically. Hydrogen atoms of the organic linkers (EDC2−, BDC2−, ADC2−, and BTC3−) and ligands (en) were placed on calculated positions and refined as riding atoms with fixed distances. Treatment of hydrogen atoms of water molecules: It was not possible to determine the positions of all hydrogen atoms of water molecules for all compounds most likely caused by a severe disorder of the water molecules. For 1 the hydrogen atoms of oxygen atoms O1− O11 could be determined unambiguously in difference Fourier maps. For the final refinements restraints using the DFIX and DANG35 commands were used and Uiso was fixed to 500 pm2. An additional peak was assigned to oxygen atom O20. After several refinements cycles its occupancy refined to ∼0.25. In the final refinement this value was fixed, which resulted in a meaningful Uiso. No hydrogen atoms were found for this water molecule O20. For 2 only a few of the hydrogen positions of water molecules O1−O20 could be identified in difference Fourier maps. As none of them could be refined in a stable way even using DFIX and DANG commands they were not included in the final refinement. The high remaining electron density (Δρmax = 1.98 × 10−6 pm−3) is located close to the [Co(en)3]3+ core. For 3 all hydrogen atoms of oxygen atoms O1−O4 could be determined unambiguously in difference Fourier maps. They were refined without any restraints using a fixed Uiso = 500 pm2. In 4 the strongest disorder of water molecules was found even at 170 K. Only a few of the hydrogen positions of water molecules O1−O14 could be identified in difference Fourier maps, but a stable refinement was not possible even with restraints. So they were omitted in the final refinement. Additionally only O1−O8 were refined anisotropically, whose positions are fully occupied. For O9−O14 the occupancies refined to values significantly lower than 1. Between O10 and O13 distances < 130 pm were found. Thus, the occupancies were set to 0.5 and the refinement of Uiso led to meaningful values. For O9, O11, O12, and O14 Uiso was fixed to 500 pm2 and the occupancies were refined. The high remaining electron density (Δρmax = 2.15 × 10−6 pm−3) is located close to the [Co(en)3]3+ core. But as checkcif detects some solvent accessible voids the existence of further water molecules with very low occupancies cannot be excluded. For 5 all hydrogen atoms of oxygen atoms O1 and O2 could be determined unambiguously in difference Fourier maps. They were refined using DFIX. More details of the structural analysis37 are given in Table 6. Selected interatomic distances and angles are listed in Tables 1−5.
immediately after the crystals were isolated from the mother liquor (see below). As no reliable elemental analysis could be conducted on these unstable compounds no such data with one exception are given in the following. For the same reason no yield is reported. 1 ∞{Λ-[Co(en)3]EDC3/2}·5.625H2O (1). In a brown sample vial Ag2EDC (0.66 g, 2 mmol) was added to a stirred aqueous solution of Λ-[Co(en)3]I3 (0.62 g, 1 mmol, 20 mL of H2O). After 5 h the light gray precipitate was filtered off and discarded. The resulting orange solution was covered with a perforated snap cap. After several days at room temperature orange single crystals of 1 grew within the nearly dried up solution. 1 ∞{Λ-[Co(en)3]BDC3/2}·10H2O (2). In a brown sample vial a suspension of solid [Ag(en)][Ag(BDC)] (0.46 g, 1 mmol) in 5 mL of ethanol was added to a stirred aqueous solution of Λ-[Co(en)3]I3 (0.43 g, 0.7 mmol, 15 mL of H2O). After 5 h the light gray precipitate was filtered off and discarded. The resulting orange solution was covered with a perforated snap cap. After several days at room temperature orange single crystals of 2 grew within the nearly dried up solution. 2 ∞{[Co(en)3]ADC3/2}·4H2O (3). In a brown sample vial solid PbADC (0.48 g, 1.5 mmol) was added to a stirred aqueous solution of rac-[Co(en)3]I3 (0.62 g, 1 mmol, 20 mL of H2O). After 5 h the light gray precipitate was filtered off and discarded. The resulting orange solution was covered with a perforated snap cap. After several days at room temperature orange single crystals of 3 grew within the nearly dried up solution. 3 is the most stable compound of the whole series. A synchrotron powder diffraction pattern (DELTA, beamline BL 9, λ = 55.1155 pm, MAR 345 detector, 295 K) recorded with a sample sealed in a capillary (ϕ 0.5 mm) confirmed that 3 can be obtained in bulk quantities and is stable for at least several days under these conditions. But a broad feature at 2θ ≈ 4° indicates a starting decomposition (Figure 1), which is also reflected in the elemental analysis for CoC12H32N6O10 (479.43): calcd C, 30.07%, N, 17.53%, H, 6.73%; found C, 28.78%, N, 17.52%, H, 6.68%.
Figure 1. Synchrotron powder diffraction pattern of 3 (DELTA, beamline BL 9, λ = 55.1155 pm, MAR 345 detector, 295 K): the recorded pattern is given in purple, and the blue pattern was calculated based on the single crystal structure data. 2 ∞{[Co(en)3]BTC}·5.55H2O (4). In a brown sample vial solid (NH4)[Ag5(BTC)2(NH3)(H2O)2] (0.23 g, 0,22 mmol) was added to a stirred aqueous solution of rac-[Co(en)3]I3 (0.26 g, 0.43 mmol, 7 mL of H2O). After 5 h the light gray precipitate was filtered off and discarded. The resulting orange solution was covered with a perforated snap cap. After several days at room temperature orange single crystals of 4 grew within the nearly dried up solution. 2 ∞{Δ-[Co(en)3]EDC(NO3)}·2 H2O (5). Single crystals of 5 were obtained as a byproduct of the attempted synthesis of Δ-1. The nitrate anion in the crystal structure can obviously be ascribed to unreacted AgNO3 in the synthesis of the starting material Ag2EDC.
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RESULTS AND DISCUSSION Compounds 1−5 contain the well-known complex [Co(en)3]3+24 as cores of supramolecular networks. These complexes are connected via second-sphere hydrogen bonding 5403
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solutions by addition of silver salts of the respective polycarboxylate ligands, e.g.
Table 1. Selected Interatomic Distances/pm in 1 Co1−N2 Co1−N6 Co1−N3 Co1−N1 Co1−N4 Co1−N5
196.2(3) 196.8(2) 196.9(2) 197.2(3) 197.2(3) 197.2(3)
Co2−N12 Co2−N7 Co2−N9 Co2−N11 Co2−N10 Co2−N8
196.3(3) 196.5(3) 196.6(3) 196.7(2) 196.7(3) 197.5(2)
Co1−C14 Co1−C15 Co1−C16 Co2−C13 Co2−C17 Co2−C18
466.8(3) 442.7(3) 443.3(3) 460.6(3) 442.4(3) 440.8(3)
[Co(en)3 ]I3 + Ag 3[C6H3(COO)3 ] → [Co(en)3 ][C6H3(COO)3 ] + 3AgI↓
Only in the almost completely evaporated aqueous solutions the respective [Co(en)3]-polycarboxylates crystallize. As no silver acetylenedicarboxylate is known, the respective lead salt was used instead. In [Co(en)3]3+ Co3+ is coordinated octahedrally by the nitrogen atoms of three chelating ethylenediamine (en) ligands.24 Depending upon the spatial arrangement of these ligands two enantiomeric forms exist, which are mirror images of each other. These enantiomers are called Λ- and Δ[Co(en3)]3+ (Figure 2). In a typical synthesis a racemate of both enantiomers is formed, but the resolution of such a racemate is well described in the literature.25 So the scope of this contribution was to show that [Co(en)3]3+ can act as a node in supramolecular polymers and that the chirality of the complex is maintained during the synthesis thus leading to non-centrosymmetric polymers crystallizing in chiral space groups. Five new compounds were synthesized, which depending upon the chirality of the starting complex contain Λ-[Co(en)3]3+ (1, 2), Δ[Co(en)3]3+ (5), or rac-[Co(en)3]3+ (3, 4). In all compounds [Co(en)3]3+ is connected via N−H···O hydrogen bonds with the polycarboxylate linker and water molecules. Because of steric and electronic effects T-shaped nodes are formed in 1−4 considering only the polycarboxylates, whereas in 5 additional interactions with the NO3− ligand must be considered. In Figure 3 a typical hydrogen bonding network
Table 2. Selected Interatomic Distances/pm in 2 Co1−N3 Co1−N4 Co1−N6 Co1−N2 Co1−N1 Co1−N5
195.0(4) 195.2(4) 195.4(3) 195.5(5) 196.4(4) 197.1(4)
Co2−N9 Co2−N12 Co2−N11 Co2−N7 Co2−N10 Co2−N8
193.2(7) 194.2(6) 194.8(6) 195.8(7) 196.9(6) 197.3(7)
Co1−C16 Co1−C17 Co1−C18 Co2−C13 Co2 − C14 Co2 − C15
464.1(9) 439.5(6) 441.7(6) 439.4(6) 440.7(6) 466.3(8)
Table 3. Selected Interatomic Distances/pm in 3a Co1−N6 Co1−N5 Co1−N1
195.1(3) 195.4(4) 195.6(5)
Co1−N3 Co1−N2 Co1−N4
196.4(3) 196.4(4) 196.9(4)
Co1−C7 Co1−C8i Co1−C9ii Co1−C9iii
434.7(5) 488.1(5) 457.3(6) 488.5(4)b
i: x + 1, y, z − 1; ii: x − 1, y, z; iii: −x + 2, −y, −z. bNot part of the SBU defined in the text. a
Table 4. Selected Interatomic Distances/pm in 4 Co1−N2 Co1−N6 Co1−N3 Co1−N1 Co1−N4 Co1−N5
195.8(6) 195.9(7) 196.0(7) 197.5(7) 198.1(6) 198.1(7)
Co2−N8 Co2−N12 Co2−N7 Co2−N11 Co2−N9 Co2−N10
190.6(8) 191.4(10) 194.5(8) 197.7(8) 199.4(10) 200.2(8)
Co1−C13 Co1−C15 Co1−C18 Co2−C14 Co2−C16 Co2−C17
483.6(8) 464.6(7) 441.8(8) 445.6(9) 466.7(8) 479.9(8)
Table 5. Selected Interatomic Distances/pm in 5 Co1−N1 Co1−N2 Co1−N3
197.2(2) 2x 196.0(2) 2x 196.2(2) 2x
Co2−N4 Co2−N5 Co2−N6
196.3(2) 2x 196.8(3) 2x 196.8(3) 2x
interactions with the linking polycarboxylate ligands. Solvent water molecules fill the space between the polymeric units. They are weakly bound via hydrogen bonds. Thus, the resulting compounds/crystals are very unstable with respect to loss of these weakly bound solvent molecules. On the other hand the interaction of typical anions used in such syntheses (I−, NO3−, etc.) with the complex cation is stronger than the interaction with polycarboxylates (cf. the easy incorporation of NO3− in compound 5). Therefore such anions have to be removed before crystallizing [Co(en)3]-polycarboxylates. We developed a synthesis in which these anions are precipitated in aqueous
Figure 3. Typical coordination sphere around the [Co(en)3]3+ complex in compounds 1−4 showing N−H···O hydrogen bonds as well as a yellow sphere (radius: 200 pm), which will replace the complex in some of the following figures.
Figure 2. Schematic view of the two enantiomers Λ- and Δ-[Co(en)3]3+. 5404
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between the [Co(en)3]3+ core and carboxylate groups is shown. Following the formalism of secondary building units (SBU)38 one can denominate the carboxylate carbon atoms as points of extension. The resulting T-shaped geometry is also visible in Figure 3. As the resulting crystal structures of 1−5 are very complex, in the following figures the [Co(en)3]3+ core is reduced to a yellow sphere, which is also shown in Figure 3. 1 ∞{Λ-[Co(en)3]EDC3/2}·5.625 H2O (1) crystallizes in the chiral space group P21 (No. 4) with Z = 4. Enantiopure Λ[Co(en)3]I3 was used as the starting material. The asymmetric unit consists of two crystallographically distinct Co atoms, each located on the general position 2a. Both are coordinated by three en ligands in way that the Λ-enantiomer is formed (Figure 4). The resulting Flack parameter (−0.003(11), Table
ladder-like structural motif (Figure 5). Defining the carboxylate carbon atoms as points of extension a T-shaped secondary building unit (SBU) is formed.38 The distances within this SBU are given in Table 1. These SBUs are connected via the EDC2− linker forming a 1D ladder-like structure. This ladder motif is not rectangular, but slightly distorted (Co2ii−Co1−Co1i = 76.950(3)°; i: x, y, z + 1; ii: x + 1, y, z). The carboxylate groups of the EDC2− linkers are not coplanar. The planes defined by the carboxylate groups are tilted by 3.9(2)°, 8.9(3)°, and 23.5(5)°, respectively, to each other. 1 ∞{Λ-[Co(en)3]BDC3/2}·10H2O (2) crystallizes in the chiral space group P1 (No. 1) with Z = 2. Enantiopure Λ-[Co(en)3]I3 was used as the starting material. The asymmetric unit consists of two crystallographically distinct Co atoms. Both are coordinated by three en ligands to form the Λ-enantiomer (Figure 6). The resulting Flack parameter (0.036(16), Table 6) confirms the acentric space group P1. Furthermore, the asymmetric unit contains three BDC2− ligands and 20 water molecules. For none of them the hydrogen positions could be refined in a stable way so that no hydrogen bonds between these water molecules and the BDC2− and en ligands shall be discussed in the following. But the O···O distances between these water oxygen atoms are in a reasonable range starting at 263.3(13) pm (O14···O15). N−H···O hydrogen bonds are formed between the nitrogen atoms of the en ligands and the oxygen atoms of the carboxylate groups of the BDC2− linker. The shortest distances are found between H11B and O15A (194.3(7) pm; O15A···N11 = 282.6(10) pm; O15A···H11B−N11 = 166.5(5)°) and H3B and O16B (196.1(6) pm; O16B···N3 = 283.3(8) pm; O16B···H3B−N3 = 162.9(3)°). Each [Co(en)3]3+ complex is connected via N−H···O hydrogen bonds with three BDC2− ligands thus forming a Tshaped motif. The BDC2− linkers connect each [Co(en)3]3+ core with three further cores thus forming a 1D ladder-like structural motif (Figure 7). The distances within the T-shaped SBU (Co−C(carboxylate)) are given in Table 2. The ladder motif is almost rectangular with Co1i−Co2−Co2ii = 85.886(4)° (i: x + 1, y + 1, z + 1; ii: x, y + 1, z − 1). As expected for terephthalates the carboxylate groups within a BDC2− linker are almost coplanar: 4.9(10)°, 7.2(4)°, and 10.4(6)°. 2 ∞{[Co(en)3]ADC3/2}·4H2O (3) crystallizes in the triclinic space group P1̅ (No. 2) with Z = 2. Racemic [Co(en)3]I3 was used as the starting material. The asymmetric unit consists of one crystallographically distinct Co atom located on the general position 2i. As both the Λ- and Δ-enantiomer of [Co(en)3]3+ exist the inversion symmetry of P1̅ is generated (Figure 8). Besides the [Co(en)3]3+ complex the asymmetric unit of 3 contains four water molecules and 1.5 ADC2− anions. 3 is the most stable compound of the whole series with respect to dehydration. Therefore the water molecules including the hydrogen positions were determined and refined unambiguously already from room temperature X-ray single crystal diffraction data. The shortest N−H···O hydrogen bond is formed between H5D of an en ligand and O9B of a carboxylate group of the ADC2− ligand (H5D···O9B = 196.5(4) pm; O9B···N5 = 286.1(6) pm; O9B···H5D−N5 = 173.5(3)°). Some further weak N−H···O hydrogen bond interactions in the range 200− 220 pm are found between the en ligand and oxygen atoms of carboxylate groups, but no such interactions are found between the en ligands and water molecules. Water molecules are only involved in shorter O−H···O hydrogen bonds with the
Figure 4. ORTEP plot of the asymmetric unit of 1 with 50% probability thermal ellipsoids and the atom-numbering scheme. For clarity water molecules are omitted.
6) confirms the chiral space group P21. Furthermore, there are three EDC2− ligands and 11 water molecules in the asymmetric unit (O1−O11). O20 was also assigned to a water molecule. Its occupancy refined to 0.25. No hydrogen atoms could be found, but the closest O···O distances to other oxygen atoms are reasonable starting at 276.2(11) pm (O20···O18A). N−H···O hydrogen bonds are formed between the nitrogen atoms of the en ligands and the oxygen atoms of the carboxylate groups of the EDC2− linker and the water molecules. The shortest distances are found between H3A and O15A (195.2(2) pm; O15A···N3 = 284.9(3) pm; O15A···H3A−N3 = 174.1(2)°) and H11B and O13B (199.7(3) pm; O13B···N11 = 288.5(4) pm; O13B···H11B− N11 = 168.9(2)°). Shorter hydrogen bonds are found between the EDC2− linker and water molecules. The shortest are O13A···H3F (174(4) pm; O13A···O3 = 262.9(4) pm; O13A···H3F−O3 = 170(4)°) and O14A···H10F (176(4) pm; O14A···O10 = 261.0(4) pm; O14A···H10F−O10 = 161(4)°). Each [Co(en)3]3+ complex is connected via N−H···O hydrogen bonds with three crystallographically distinct EDC2− ligands thus forming the T-shaped motif already shown in Figure 3. Via the EDC2− linkers each [Co(en)3]3+ core is connected with three other cores thus forming a 1D 5405
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Table 6. Details of X-ray Single-Crystal Structure Analysis of Compounds 1−5 formula formula weight [g mol−1] crystal description crystal size [mm] space group Z a [pm] b [pm] c [pm] α [deg] β [deg] γ [deg] V [× 106 pm3] calc density [g cm−3] absorption correction diffractometer, radiation temperature [K] 2θmax [deg] index ranges
reflections collected/independent significant reflections (I > 2σ(I)) R(int) data/parameters/restraints GOF = Sall R [F2 > 2σ(F2)] wR(F2) Δρmax/Δρmin [× 10−6 pm−3] Flack parameter
1
2
3
4
5
CoC12H38.25N6O11.625 511.74 plate, orange 0.50 × 0.40 × 0.10 P21 (No. 4) 4 888.60(7) 2116.4(2) 1270.1(1) 90 103.424(6) 90 2323.3(3) 1.462 numerical IPDS II, Mo Kα 170(2) 54.2 −11 ≤ h ≤ 11 −27 ≤ k ≤ 27 −16 ≤ l ≤ 16 36869/10310 9040 0.060 10310/621/34 1.05 0.037 0.099 0.80/−0.44 −0.003(11)
CoC18H50N6O16 665.67 block, orange 0.30 × 0.20 × 0.20 P1 (No. 1) 2 1071.30(5) 1152.20(5) 1355.80(6) 70.415(4) 85.157(4) 80.418(4) 1553.98(12) 1.422 numerical IPDS 2T, Mo Kα 170(2) 53.6 −13 ≤ h ≤ 13 −14 ≤ k ≤ 14 −16 ≤ l ≤ 17 15682/10820 10187 0.065 10820/739/3 1.08 0.066 0.189 1.98/−0.66 0.036(16)
CoC12H32N6O10 479.43 block, orange 0.30 × 0.20 × 0.20 P1̅ (No. 2) 2 856.45(14) 1086.7(2) 1235.2(2) 87.53(2) 72.56(2) 71.34(2) 1037.3(3) 1.532 numerical IPDS I, Mo Kα 293(2) 50.0 −10 ≤ h ≤ 10 −12 ≤ k ≤ 12 −14 ≤ l ≤ 14 8810/3648 1770 0.122 3433/288/7 0.74 0.046 0.077 0.44/−0.62
CoC15H38.1N6O11.55 546.42 needle, orange 0.60 × 0.20 × 0.10 P21/c (No. 14) 8 1660.0(2) 1600.30(11) 1980.84(12) 90 97.95(1) 90 5211.4(8) 1.395 numerical IPDS II, Mo Kα 170(2) 54.8 −21 ≤ h ≤ 20 −20 ≤ k ≤ 20 −25 ≤ l ≤ 25 80297/11644 5099 0.125 11644/592/0 0.92 0.103 0.303 2.15/−0.74
CoC10H30N7O9 451.40 plate, orange 0.40 × 0.40 × 0.20 C2 (No. 5) 4 1804.30(11) 1173.40(7) 1001.00(7) 90 120.189(3) 90 1831.8(2) 1.636 numerical Nonius Kappa CCD, Mo Kα 100(2) 60.0 −25 ≤ h ≤ 18 −16 ≤ k ≤ 14 −5 ≤ l ≤ 14 5740/4225 3862 0.033 4225/263/5 1.02 0.035 0.087 0.34/−0.56 −0.003(14)
Figure 5. 1D ladder-like structural motif in the crystal structure of 1. [Co(en)3]3+ cores are shown as yellow spheres and EDC2− ligands in wire style. N−H···O hydrogen bonds are indicated as broken lines. Water molecules are omitted.
Co1−Co1ii = 84.962(7)°; i: −x, −y, −z; ii: x + 1, y, z − 1). These SBUs are connected via additional N−H···O hydrogen bonds between en and ADC2− to form dimers. Via these dimers the ladders are connected to build up corrugated layers, which are shown in Figure 9. The carboxylate groups of one ADC2− linker are coplanar, whereas for the other crystallographically distinct ADC2− linker a torsion angle of 57.0(3)° is found between the planes defining both carboxylate groups. 2 ∞{[Co(en)3]BTC}·5.55H2O (4) crystallizes in the space group P21/c with Z = 8. Racemic [Co(en)3]I3 was used as the
carboxylate groups of the ADC2− ligands starting at 179(3) pm (O7B···H2E; O7B···O2 = 273.5(5) pm; O7B···H2E−O2 = 165(4)°) or with other water molecules starting at 185(3) pm (O1···H3E; O1···O3 = 278.3(6) pm; O1···H3E−O3 = 162(4)°). Each [Co(en)3]3+ complex is connected via N−H···O hydrogen bonds with ADC2− ligands thus forming a slightly distorted T-shaped motif. The distances within this SBU are given in Table 3. These SBUs are connected by the ADC2− ligands to form a ladder-like motif as found in 1 and 2 (Co1i− 5406
dx.doi.org/10.1021/cg3010085 | Cryst. Growth Des. 2012, 12, 5402−5410
Crystal Growth & Design
Article
Figure 8. ORTEP plot of the asymmetric unit of 3 with 50% probability thermal ellipsoids and the atom-numbering scheme.
Figure 6. ORTEP plot of the asymmetric unit of 2 with 50% probability thermal ellipsoids and the atom-numbering scheme. For clarity water molecules are omitted.
starting material. The asymmetric unit contains two crystallographically distinct Co atoms on the general position 4e. Because of the inversion symmetry of P21/c both the Λ- and Δenantiomer of [Co(en)3]3+ exist (Figure 10). Besides two [Co(en)3]3+ complexes the asymmetric unit contains two BTC3− ligands and 14 positions, which were assigned to oxygen atoms of water molecules. For none of them the hydrogen positions could be determined and refined unambiguously. So they were omitted in the final refinements. Furthermore, only O1−O8 were refined with full occupancies, whereas for O9− O14 only partly occupied sites were found. Thus, the discussion of hydrogen bonds will be restricted to interactions between en ligands and BTC3− linkers. The shortest N−H···O hydrogen bonds are found between O15B and H3C (197.9(5) pm; O15B···N3 = 284.8(8) pm; O15B···H3C−N3 = 162.1(4)°) and O16A and H12D (198.9(7) pm; O16A···N12 = 284.9(13) pm; O16A···H12D−N12 = 159.3(7)°). Each [Co(en)3]3+ complex is connected via N−H···O hydrogen bonds with three BTC3− ligands thus forming a
Figure 9. 2D layers in the crystal structure of 3. [Co(en)3]3+ cores are shown as yellow spheres and ADC2− ligands in wire style. N−H···O hydrogen bonds are indicated as broken lines. Water molecules are omitted.
Figure 7. 1D ladder-like structural motif in the crystal structure of 2. [Co(en)3]3+ cores are shown as yellow spheres and BDC2− ligands in wire style. N−H···O hydrogen bonds are indicated as broken lines. Water molecules are omitted. 5407
dx.doi.org/10.1021/cg3010085 | Cryst. Growth Des. 2012, 12, 5402−5410
Crystal Growth & Design
Article
the starting material Ag2EDC. The asymmetric unit contains of two crystallographically distinct [Co(en)3]3+ units, both in the Δ-configuration (Figure 12). The Co atoms are placed on the
Figure 10. ORTEP plot of the asymmetric unit of 4 with 50% probability thermal ellipsoids and the atom-numbering scheme. For clarity water molecules are omitted. Figure 12. ORTEP plot of the asymmetric unit of 5 with 50% probability thermal ellipsoids and the atom-numbering scheme.
slightly distorted T-shaped motif. The distances within this SBU are given in Table 4. These SBUs are connected by the trifunctional BTC3− ligands to form corrugated 63 layers, which are shown in Figure 11. The carboxylate groups of the BTC3− linkers are twisted out of the plane of the aryl ring. The respective angles are 3.3(3)°, 7.7(5)°, 21.8(6)° for linker 1 and 3.6(7)°, 22.2(6)°, 31.2(4)° for linker 2. 2 ∞{Δ-[Co(en)3]EDC(NO3)}·2H2O (5) crystallizes in the chiral space group C2 (No. 5) with Z = 4. Single crystals of 5 were obtained during the attempted synthesis of Δ-1 using enantiopure Δ-[Co(en)3]I3. Single crystals of Δ-1 could not be obtained up to now. The incorporation of NO3− in the crystal structure of 5 can obviously be ascribed to unreacted AgNO3 in
special positions 2a and 2b. The resulting Flack parameter (−0.003(14), Table 6) confirms the acentric space group C2. Besides the [Co(en)3]3+ units the asymmetric unit of 5 consists of two water molecules, one EDC2− linker and two NO3− groups, the latter also placed on special positions. All hydrogen positions were determined and refined unambiguously. O···H hydrogen bonds
