Article pubs.acs.org/crystal
Flexible Bis(imidazole) Mediated Assembly of Silver(I)−Organic Frameworks with Ethynide and Trifluoroacetate Ligands Jin Yang,†,§ Ting Hu,‡,§ and Thomas C. W. Mak*,§ †
Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024, People’s Republic of China Xiamen Institute of Rare Earth Materials, Chinese Academy of Sciences, Xiamen 361021, People’s Republic of China § Department of Chemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, People’s Republic of China ‡
S Supporting Information *
ABSTRACT: A new family of 10 organosilver(I) complexes, namely, [(AgC CPh)2(AgO2CCF3)4(cis-1,2-bix)(CH3OH)]·2CH3OH (1,2-bix = 1,2-bis(imidazol-1ylmethyl)benzene, 1A), [(AgCCC6H4Me-2)2(AgO2CCF3)4(cis-1,3-bix)]·5.25H2O (1,3-bix = 1,3-bis(imidazol-1-ylmethyl)benzene, 1B), [(AgCCPh)3(AgO2CCF3)6(trans-1,4-bix)(CH3OH)3]·2CH3OH (1,4-bix = 1,4-bis(imidazol-1-ylmethyl)benzene, 2A), [(AgCCC 6H 4Me-4) 3(AgO 2CCF 3) 6 (trans-1,4-bix)(CH 3OH) 3 ]·2CH 3OH (2B), [(AgCCPh)(AgO2CCF3)3(trans-1,3-bix)(H2O)]·0.5H2O (3A), [(AgC CC6H4Me-4)(AgO2CCF3)3(trans-1,3-bix)(H2O)] (3B), [(AgCCC6H4Me-4)(AgO 2CCF 3 ) 3 (bbi)(H2 O)] (bbi = 1,1′-(1,4-butanediyl)bis(imidazole), 3C), [(AgCCC6H4tBu-4)(AgO2CCF3)3(trans-1,4-bix)] (3D), [(AgCCPh)2(AgO2CCF3)4(bbi)(H2O)]·2H2O (4), and [(AgCCtBu)2(AgO2CCF3)4(bbi)] (5), have been synthesized employing a variable combination of ethynide, trifluoroacetate, and bridging bis(imidazole) ligands. In both 1A and 1B, the flexible 1,2-bix or 1,3-bix ligands in cis-conformations are alternatively attached on both sides of an infinite cationic silver(I) chain, and neighboring organosilver(I) chains are further interconnected by intermolecular hydrogen bonds to generate a three-dimensional supramolecular architecture. In structural analogues 2A and 2B, pairs of silver(I) chains are linked via the trans-1,4-bix ligands to yield infinite ladders, which are further joined together by hydrogen bonds to afford a three-dimensional supramolecular network. In the isostructural series 3A−3D, centrosymmetric (PhC2)2Ag8 aggregates are connected by trifluoroacetate groups to give an infinite chain, and such chains are then bridged by bis(imidazole) ligands to generate a coordination layer. Furthermore, adjacent layers are linked by hydrogen bonds to form a three-dimensional supramolecular network. In 4, infinite silver(I)−phenylethynide chains constructed by Ag6 aggregates are bridged by bbi ligands in a gauche−trans−gauche conformation to yield a threedimensional coordination framework. In contrast, infinite silver(I)-tert-butylethynide chains based on Ag8 and Ag6 aggregates in 5 are linked by bbi ligands exhibiting different trans−trans−trans and gauche−trans−gauche conformations to generate a threedimensional coordination network. Finally, the roles played by various bis(imidazole) ligands and ethynides bearing different substituents in the framework assembly are discussed in detail.
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(SBUs), can be utilized to construct high-nuclearity clusters,7 as well as coordination6 and supramolecular networks.8 In such systems, an ethynide group usually interacts with 3−5 silver(I) ions to generate a SBU, the structure of which depends on the reaction and crystallization conditions. Our past systematic investigation into the silver(I) double and multiple salts of Ag2 C 2 (silver acetylenediide or ethynediide) indicates that the introduction of coexisting anions and ancillary ligands, such as polyoxometalate,9 betaine,10 crown ether,11 and nitrogen-containing donor ligands,6a−j can effectively control the structure diversity of the products. Very recently, we have introduced various types of nitrogen-containing donor ligands into the Ag2C4 reaction
INTRODUCTION Metal−ethynide complexes have received intense interest because of their structural diversity1 and potential applications in photoluminescence,2 nonlinear optics,3 and rigid-rod molecular wires.4 Generally, the ethynide moiety can induce metallophilic interaction between coinage metal(I) centers, such as Cu, Ag, and Au, through diverse coordination modes, resulting in the formation of clusters, multinuclear aggregates, or extended solid-state architectures.5 In this regard, we have initiated a systematic investigation on the synthesis and structural characterization of crystalline silver(I) complexes with various ethynide-containing ligands, including the dianions C2 2−, C 42−, C 62−, C 82−, and C 6H 4 2−, and carbon-rich monoanions of the type R−C2− (R = alkyl, aryl, heteroaryl) over the past dozen years.6 It is now well-established that multinuclear silver(I)−ethynide supramolecular synthons, functioning as versatile organometallic structure building units © 2014 American Chemical Society
Received: February 24, 2014 Revised: April 28, 2014 Published: May 1, 2014 2990
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system and achieved a multidimensional coordination network assembly.6g In contrast, double and multiple silver(I) salts of silver(I) aryl ethynide have not been well-studied because of their low solubility in a concentrated aqueous solution of a soluble silver(I) salt.12 The incorporation of ancillary ligands provided a feasible route for the assembly of silver(I) aryl ethynide. So far, studies on silver(I) aryl ethynide complexes with ancillary ligands have been focused on species that incorporate simple phosphine or dimethyl sulfoxide (DMSO) ligands.12 However, the domain of double and multiple salts of silver(I) aryl ethynide bearing ancillary nitrogen-containing donor ligands still remains relatively unexplored.2a To our knowledge, thus far, only two examples of silver(I) aryl ethynide aggregates with multidentate nitrogen-containing donor ligands have been documented.2a On the other hand, our previous investigation on silver(I) aryl ethynide complexes have demonstrated that argentophilic aggregation accounts for the formation of clusters, chains, and layers, and the structural patterns of silver(I) chains can be fine-tuned by the presence of different ancillary anions.12 It is, therefore, anticipated that finetuning with selected nitrogen-containing donor ligands may induce the silver(I) aggregate at each ethynide terminus to adjust its coordination environment, thereby leading to variation of silver(I) chain patterns and dimensionalities of coordination networks. In view of the above considerations, we set out to conduct a follow-up investigation employing silver(I) ethynides and conformationally flexible bridging ligands containing nitrogendonor sites as structure-directing components, such as 1,2bis(imidazol-1-ylmethyl)benzene (abbreviated as 1,2-bix), 1,3bis(imidazol-1-ylmethyl)benzene (1,3-bix), 1,4-bis(imidazol-1ylmethyl)benzene) (1,4-bix), and 1,1′-(1,4-butanediyl)bis(imidazole) (bbi).13 Herein, we report the synthesis and structural characterization of 10 new silver(I)−organic complexes based on different combinations of ethynides and bridging bis(imidazole) ligands (Chart 1), namely, [(AgCCPh)2(AgO2CCF3)4(cis-
Article
EXPERIMENTAL SECTION
Reagents and Instruments. All chemicals obtained from commercial sources were of analytically pure grade and used without further purification. The bis(imidazole) ligands 1,n-bix and bbi were prepared following the literature method.13 Polymeric [AgCCR]n (R = tBu, Ph, C6H4Me-2, C6H4Me-4, and C6H4tBu-4) were prepared according to the literature procedure.12b IR spectra were recorded on KBr pellets at room temperature on a Nicolet Impact 420 FT-IR spectrometer in the range of 4000−400 cm−1 at a resolution of 2 cm−1. Elemental analysis (C, H, N) was performed on a PerkinElmer 240 elemental analyzer. Caution! Silver−ethynide complexes are potentially explosive in the dry state when subjected to heating or mechanical shock and should be handled in small quantities with extreme care. Syntheses and Characterization. [(AgCCPh)2(AgO2CCF3)4(cis-1,2-bix)(CH3OH)]·2CH3OH (1A). Moist AgCCPh (∼0.10 g) was added to 3 mL of a methanol solution of AgCF3COO (0.15 g, 1 mmol) in a beaker. After stirring for about 10 min, the mixture was filtered. Next, 1,2-bix (0.12 g, 0.5 mmol) was added. After stirring for another 5 min, the mixture was filtered. Pale yellow crystals of 1A were obtained at room temperature after several days in 31% yield. IR: ν = 1987 cm−1 (w, νCC); Anal. Calcd (%) for C41H36Ag6F12N4O11 (Mr = 1635.96): C 30.10, H 2.22, N 3.42. Found: C 30.92, H 1.72, N 3.62. [(AgCCC6 H 4 Me-2) 2 (AgO2 CCF 3 ) 4 (cis-1,3-bix)]·5.25H 2 O (1B). Compound 1B was synthesized in a similar manner to compound 1A using AgCCC6H4Me-2 and 1,3-bix instead of AgCCPh and 1,2-bix. Pale yellow crystals of 1B were obtained at room temperature after several days in 33% yield. IR: ν = 1980 cm−1 (w, νCC); Anal. Calcd (%) for C80H72Ag12F24N8O26.50 (Mr = 3319.90): C 28.94, H 2.19, N 3.38. Found: C 28.20, H 1.58, N 3.58. [(AgCCPh)3(AgO2CCF3)6(trans-1,4-bix)(CH3OH)3]·2CH3OH (2A). Compound 2A was synthesized in a similar manner to compound 1A using 1,4-bix instead of 1,2-bix. Pale yellow crystals of 2A were obtained at room temperature after several days in 43% yield. IR: ν = 2007 cm−1 (w, νCC); Anal. Calcd (%) for C55H49Ag9F18N4O17 (Mr = 2350.78): C 28.10, H 2.10, N 2.38. Found: C 27.61, H 2.07, N 2.33. [(AgCCC 6 H 4 Me-4) 3 (AgO 2 CCF 3 ) 6 (trans-1,4-bix)(CH 3 OH) 3 ]· 2CH3OH (2B). Compound 2B was synthesized in a similar manner to compound 1A using AgCCC6H4Me-4 and 1,4-bix instead of AgC CPh and 1,2-bix. Pale yellow crystals of 2B were obtained at room temperature after several days in 27% yield. IR: ν = 1979 cm−1 (w, νCC); Anal. Calcd (%) for C58H55Ag9F18N4O17 (Mr = 2392.89): C 29.11, H 2.32, N 2.34. Found: C 29.17, H 1.97, N 2.18. [(AgCCPh)(AgO2CCF3)3(trans-1,3-bix)(H2O)]·0.5H2O (3A). Compound 3A was synthesized in a similar manner to 1A using 1,3-bix instead of 1,2-bix. Pale yellow crystals of 3A were obtained at room temperature after several days in 29% yield. IR: ν = 1971 cm−1 (w, νCC); Anal. Calcd (%) for C56H41Ag8F18N8O15 (Mr = 2270.89): C 29.62, H 1.82, N 4.93. Found: C 29.28, H 1.95, N 4.59. [(AgCCC6H4Me-4)(AgO2CCF3)3(trans-1,3-bix)(H2O)] (3B). Compound 3B was synthesized in a similar manner to compound 1A using AgCCC6H4Me-4 and 1,3-bix instead of AgCCPh and 1,2-bix. Pale yellow crystals of 3B were obtained at room temperature after several days in 38% yield. IR: ν = 1959 cm−1 (w, νCC); Anal. Calcd (%) for C29H23Ag4F9N4O7 (Mr = 1141.98): C 30.50, H 2.03, N 4.91. Found: C 30.64, H 2.08, N 4.79. [(AgCCC6H4Me-4)(AgO2CCF3)3(bbi)(H2O)] (3C). Compound 3C was synthesized in a similar manner to compound 1A using AgC CC6H4Me-4 and bbi instead of AgCCPh and 1,2-bix. Pale yellow crystals of 3C were obtained at room temperature after several days in 24% yield. IR: ν = 1962 cm−1 (w, νCC); Anal. Calcd (%) for C25H23Ag4F9N4O7 (Mr = 1093.93): C 27.45, H 2.12, N 5.12. Found: C 27.17, H 1.83, N 5.24. [(AgCCC6H4tBu-4)(AgO2CCF3)3(trans-1,4-bix)] (3D). Compound 3D was synthesized in a similar manner to compound 1A using AgC CC6H4tBu-4 and 1,4-bix instead of AgCCPh and 1,2-bix. Pale yellow crystals of 3D were obtained at room temperature after several days in 33% yield. IR: ν = 1957 cm−1 (w, νCC); Anal. Calcd (%) for C32H27Ag4F9N4O6 (Mr = 1166.04): C 32.96, H 2.33, N 4.80. Found: C 30.36, H 1.96, N 4.92.
Chart 1. Flexible Bis(imidazole) Ligands Used in This Studya
a
The abbreviations 1,n-bix (n = 2, 3, 4) are used to represent the positional isomers of bis(imidazolylmethyl)benzene.
1,2-bix)(CH3OH)]·2CH3OH (1A), [(AgCCC6H4Me-2)2(AgO2CCF3)4(cis-1,3-bix)]·5.25H2O (1B), [(AgCCPh)3(AgO 2 CCF 3 ) 6 (trans-1,4-bix)(CH 3 OH) 3 ]·2CH 3 OH (2A), [(AgCCC 6 H 4 Me-4) 3 (AgO 2 CCF 3 ) 6 (trans-1,4-bix)(CH3OH)3]·2CH3OH (2B), [(AgCCPh)(AgO2CCF3)3(trans-1,3-bix)(H2O)]·0.5H2O (3A), [(AgCCC6H4Me-4)(AgO2CCF3)3(trans-1,3-bix)(H2O)] (3B), [(AgCCC6H4Me-4)(AgO2CCF3)3(bbi)(H2O)] (3C), [(AgCCC6H4tBu4)(AgO2CCF3)3(trans-1,4-bix)] (3D), [(AgCCPh)2(AgO2CCF3)4(bbi)(H2O)]·2H2O (4), and [(AgCCtBu)2(AgO2CCF3)4(bbi)] (5). 2991
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Figure 1. (a) Coordination modes of the PhCC− ligands in 1A with atom labeling. Selected bond lengths [Å]: C1C2 1.217(15), C9C10 1.217(15), Ag···Ag 2.815(2)−3.261(3). (b) Characteristic cationic silver(I) chain in 1A formed by Ag7 aggregates via bridging atoms Ag1 and Ag1A. (c) Coordination of silver(I) chain by surrounding phenylethynide anions, methanol ligands, trifluoroacetate ligands, and cis-1,2-bix ligands. (d) Packing of silver(I)−organic chains in 1A, which are linked by weak hydrogen bonds to give a three-dimensional supramolecular framework. All irrelevant hydrogen atoms are omitted for clarity. Symmetry codes: A −x, 2 − y, −z; B 1 − x, 2 − y, −z; C x, 1.5 − y, 0.5 + z; D x, 1.5 − y, −0.5 + z. [(AgCCPh)2(AgO2CCF3)4(bbi)(H2O)]·2H2O (4). Compound 4 was synthesized in a similar manner to compound 1A using bbi instead of 1,2-bix. Pale yellow crystals of 4 were obtained at room temperature after several days in 38% yield. IR: ν = 2010 cm−1 (w, νCC); Anal.
Calcd (%) for C32H30Ag6F12N4O11 (Mr = 1521.82): C 25.26, H 1.99, N 3.68. Found: C 25.19, H 1.19, N 4.08. [(AgCCtBu)2(AgO2CCF3)4(bbi)] (5). Compound 5 was synthesized in a similar manner to compound 1A using AgCCtBu and bbi 2992
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Figure 2. (a) Coordination modes of the 2-MeC6H4CC− ligands in 1B with atom labeling. Selected bond lengths [Å]: C1C2 1.225(13), C10 C11 1.249(13), Ag···Ag 2.8641(16)−3.3355(12). (b) Characteristic cationic silver(I) chain in 1B formed from the linkage of Ag8 aggregates via bridging atoms Ag5 and Ag5A. (c) Coordination of silver(I) chain by surrounding 2-MeC6H4CC− anions, trifluoroacetate ligands, and cis-1,3-bix ligands. (d) Packing of silver(I) chains in 1B, which are linked by weak hydrogen bonds to give a three-dimensional supramolecular network. All irrelevant hydrogen and fluorine atoms are omitted for clarity. Symmetry codes: A −x, 2 − y, 1 − z; B −x, 2 − y, −z; C −1 + x, y, z; D x, −1 + y, z; E x, 1 + y, z; F 1 + x, y, z. Single-Crystal Structure Determination. Crystal data were collected on a Bruker Smart Apex II CCD diffractometer with Mo−Kα radiation (λ = 0.71073 Å) at 173(2) K. The intensities were corrected for Lorentz and polarization factors, as well as for absorption by the
instead of AgCCPh and 1,2-bix. Pale yellow crystals of 5 were obtained at room temperature after several days in 31% yield. IR: ν = 2011 cm−1 (w, νCC); Anal. Calcd (%) for C30H32Ag6F12N4O8 (Mr = 1451.79): C 24.82, H 2.22, N 3.86. Found: C 25.05, H 1.64, N 4.07. 2993
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Figure 3. (a) Coordination modes of the PhCC− ligands in 2A with atom labeling. Selected bond lengths [Å]: C15C16 1.217(11), C23C24 1.228(11), C31C32 1.216(10), Ag···Ag 2.8377(8)−3.3321(10). (b) Characteristic cationic silver(I) chain in 2A formed from the linkage of adjacent Ag10 aggregates via bridging atoms Ag1A and Ag3A. (c) Ladder-like structure constructed by two silver(I) chains and trans-1,4-bix ligands in 2A. (d) Packing of ladder structures in 2A, which are linked by weak hydrogen bonds to give a three-dimensional supramolecular framework. All irrelevant hydrogen and fluorine atoms are omitted for clarity. Symmetry codes: A 1 + x, y, z; B 1 + x, −1 + y, z; C 2 − x, 1 − y, −z. multiscan method.14 The structures were solved by the direct method and refined by full-matrix least-squares fitting on F2 by SHELX-97,15 and all non-hydrogen atoms were refined with anisotropic thermal parameters. In 1A, the CF3 moiety of the trifluoroacetate group exhibits rotational disorder, and the F atoms (F10, F11, F12, F10′, F11′, F12′) were each refined with half site occupancy. In 1B, the CF3 moieties of both independent trifluoroacetate groups are similarly disordered, and their F atoms (F4, F5, F6, F4′, F5′, F6′; F10, F11, F12, F10′, F11′, F12′) were refined with an assigned site-occupancy ratio of 0.75:0.25. In 2A, the CF3 moieties of both independent CF3CO2− groups are disordered, and their F atoms (F7, F8, F9, F7′,
F8′, F9′; F16, F17, F18, F16′, F17′, F18′) were refined with an assigned site-occupancy ratio of 0.75:0.25. In 2B, the CF3 moiety of the CF3CO2− group is disordered, and the F atoms (F7, F8, F9; F7′, F8′, F9′) were refined with an assigned site-occupancy ratio of 0.75:0.25. F1 and F2 of the CF3CO2− group are also disordered, and the F atoms (F1, F2, F1′, F2′) were each refined with half site occupancy. In 3B, the CF3 moiety (F4, F5, F6) of the CF3CO2− group is disordered, and the F atoms (F4, F5, F6; F4′, F5′, F6′) were refined with an assigned site-occupancy ratio of 0.75:0.25. O3 of the CF3CO2− group is also disordered, and the O atoms (O3, O3′) were refined with an assigned site-occupancy ratio of 0.75:0.25. In 3C, the CF3 moiety 2994
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(F4, F5, F6) of the CF3CO2− group is disordered, and the F atoms (F4, F5, F6; F4′, F5′, F6′) were refined with an assigned siteoccupancy ratio of 0.75:0.25. The C20 atom of the bbi ligand is also disordered, and the C atoms (C20, C20′) were each refined with half site occupancy. In 3D, the CF3 moiety (F1, F2, F3) of the CF3CO2− group is disordered, and the F atoms (F1, F2, F3; F1′, F2′, F3′) were refined with an assigned site-occupancy ratio of 0.75:0.25. The F7 atom of the CF3CO2− group is also disordered, and the F atoms (F7, F7′) were refined with an assigned site-occupancy ratio of 0.75:0.25. In 4, the F7 atom of the CF3CO2− group is disordered, and the F atoms (F7, F7′) were refined with an assigned site-occupancy ratio of 0.75:0.25. The F12 atom of the CF3CO2− group is also disordered, and the F atoms (F12, F12′) were each refined with half site occupancy.
shaped Ag4 basket in the μ4-η1,η1,η1,η2 coordination mode, whereas each ethynide group in 1B is capped by a Ag5 basket in the μ5-η1,η1,η1,η1,η2 coordination mode (Figure 2a−c). In addition, in the chain structure of 1B, the Ag···Ag separation of ca 4.449 Å by cis-1,3-bix is slightly longer than that observed in 1A (ca. 4.103 Å). As in the case of 1A, adjacent pairs of phenyl rings of the 2methylphenylethynides in 1B are arranged on both sides of the silver(I) chain directed along the c axis (Figure 2c), and therefore, a similar pairwise offset face-to-face π−π interaction (intercentroid distance, 3.733 Å) also occurs between neighboring phenyl rings. Adjacent silver(I)−organic chains in 1B are further linked by intermolecular hydrogen bonds C22−H22B···F11C (C22···F11C 3.321 Å) and C22−H22A··· F8D (C22···F8D 3.558 Å) to yield a three-dimensional supramolecular architecture (Figure 2d). [(AgCCPh) 3 (AgO 2 CCF 3 ) 6 (trans-1,4-bix)(CH 3 OH) 3 ]· 2CH3OH (2A) and [(AgCCC6H4Me-4)3(AgO2CCF3)6(trans1,4-bix)(CH3OH)3]·2CH3OH (2B). To evaluate the effect of the position of the two imidazol-1-ylmethyl groups on the structures of silver(I) aggregates and the resulting network, the 1,2-bix in 1A was replaced by 1,4-bix to yield complex 2A. In the crystal structure of 2A, there are three independent phenylethynide anions that are consolidated into a Ag10 aggregate via different coordination modes. As shown in Figure 3a, the ethynide moiety C15C16 is capped by a butterflyshaped Ag4 basket in a μ4-η1,η1,η2,η2 mode, wherein three Ag··· C σ/π bonds (Ag9···C15 = 2.435(7) Å, Ag3A···C15 = 2.379(7) Å, and Ag8···C15 = 2.486(7) Å) are in the range of 2.379(7)− 2.486(7) Å, two Ag···C π-type bonds (Ag9···C16 = 2.860(7) Å and Ag3A···C16 = 2.727(7) Å) are in the range of 2.727(7)− 2.860(7) Å, and a Ag1A···C15 σ bond has a length of 2.073(7) Å. The other two ethynide groups C23C24 and C31C32 are each bound to a square-pyramidal Ag5 basket in a μ5η1,η1,η1,η2,η2 mode. Each ethynide group C23C24 involves three Ag···C σ/π interactions (Ag6···C23 = 2.376(7) Å, Ag5··· C23 = 2.488(7) Å, and Ag3···C23 = 2.567(7) Å), three Ag···C π-type bonds (Ag2···C23 = 2.364(8) Å, Ag2···C24 = 2.600(7) Å, and Ag6···C24 = 2.801(9) Å), and a Ag···C σ bond (Ag4··· C23 = 2.147(8) Å), whereas each C31C32 interacts with silver(I) through four Ag···C σ/π bonds (Ag9···C31 = 2.419(7) Å, Ag8···C31 = 2.473(7) Å, Ag5···C31 = 2.477(7) Å, and Ag6··· C31 = 2.498(7) Å), two Ag···C π-type bonds (Ag5···C32 = 2.7890(78) Å and Ag9···C32 = 2.820(8) Å), and a Ag···C σ bond (Ag7···C31 = 2.104(7) Å). The silver(I) atoms (Ag2, Ag3, Ag4, Ag5, Ag6, Ag7, Ag8, Ag9, Ag1A, and Ag3A) are joined together through argentophilic interactions to form a Ag10 aggregate (Figure 3a). Neighboring Ag10 aggregates are further fused together through two shared silver(I) atoms (Ag1A and Ag3A) to generate an infinite silver(I) chain along the a axis (Figure 3b). Notably, the phenyl rings of the phenylethynides only lie on one side of the infinite silver(I) chain, where the infinite silver(I) chain is stabilized by continuous π−π stacking of three phenyl rings (intercentroid distances (I)···(II) 3.898 Å and (II)···(III) 3.979 Å) (Figure 3b). The 1,4-bix ligands in trans-conformations bridge two adjacent silver(I) chains to afford a ladder structure (Figure 3c), with Ag−N distances of 2.102(6) and 2.149(6) Å. The Ag···Ag distance bridged by the trans-1,4-bix of ca. 14.860 Å in 2A is significantly longer than those found in both 1A (ca. 4.103) and 1B (ca 4.449 Å), attributing to the variation of the positions of two imidazol-1-ylmethyl moieties.
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RESULTS AND DISCUSSION Description of Crystal Structures. [(AgCCPh)2(AgO2CCF3)4(cis-1,2-bix)(CH3OH)]·2CH3OH (1A) and [(AgCCC6H4Me-2)2(AgO2CCF3)4(cis-1,3-bix)]·5.25H2O (1B). In the crystal structure of 1A, there are two independent phenylethynide anions exhibiting different coordination modes. As shown in Figure 1a, the ethynide group composed of C1 and C2 is capped by a square-pyramidal Ag5 basket in a μ5η1,η1,η1,η1,η2 coordination mode with Ag···C σ/π bonds (Ag1··· C1 = 2.553(10) Å, Ag3···C1 = 2.428(9) Å, and Ag4···C1 = 2.599(9) Å), two Ag···C π bonds (Ag1A···C1 = 2.390(9) Å and Ag1A···C2 = 2.681(11) Å), and a Ag···C σ bond (Ag2···C1 = 2.082(11) Å). The remaining ethynide group comprising C9 and C10 is bound to a butterfly-shaped Ag4 basket in a μ4η1,η1,η1,η2 coordination mode, forming two Ag···C σ/π bonds (Ag3···C9 = 2.391(11) Å and Ag4···C9 = 2.392(10) Å), two Ag···C π bonds (Ag6B···C9 = 2.325(10) Å and Ag6B···C10 = 2.593(11) Å), and a Ag···C σ bond (Ag5···C9 = 2.077(12) Å) (Figure 1a). As shown in Figure 1b, the silver(I) atoms (Ag1, Ag2, Ag3, Ag4, Ag5, Ag1A, and Ag6B) are united together through argentophilic interactions to form a Ag7 aggregate. Such adjacent Ag7 aggregates via bridging atoms Ag1 and Ag1A yield an infinite cationic silver(I) chain, which is stabilized by the trifluoroacetate ligands, with Ag−O bond lengths of 2.228(9)−2.389(8) Å (Figure 1c). The flexible 1,2-bix ligands in a cis-conformation are alternatively attached on both sides of the infinite silver(I)−organic chain, with Ag−N distances of 2.089(9)−2.108(9) Å. Obviously, such chelating cis-1,2-bix ligands further stabilize the silver(I)−organic chain structure through the Ag−N interactions. The Ag···Ag distance separated by cis-1,2-bix is ca. 4.103 Å. As shown in Figure 1c, the phenylethynide groups arranged on both sides of the silver(I) chain are involved in pairwise offset face-to-face π−π interaction (intercentroid distance, 4.123 Å). Further, neighboring silver(I)−organic chains in 1A are interconnected by intermolecular hydrogen bonds C28−H28···F4C (C28···F4C 3.458 Å) to produce a three-dimensional supramolecular architecture (Figure 1d). Notably, 1B was also synthesized in a similar manner to 1A by varying the substituted group of phenylethynide and the positions of two imidazol-1-ylmethyl groups on the phenyl ring. A notable finding is that, although both 1A and 1B feature chain structures, their silver(I) aggregates are completely different. In 1A, Ag4 and Ag5 baskets are united together through argentophilic interactions to give the Ag7 aggregate, which are further joined together to yield the silver(I) chain. However, in 1B, the silver(I) chain is based on the Ag8 aggregates (Figure 2a−c). This observation can be attributed to different coordination modes of the ethynides in 1A and 1B. The ethynide group C9C10 in 1A is bound to a butterfly2995
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Figure 4. (a) Coordination modes of the PhCC− ligands in 3A with atom labeling. Selected bond lengths [Å]: C1C2 1.213(10), Ag···Ag 2.8813(10)−3.1140(7). (b) Characteristic chain structure in 3A formed from the linkage of Ag8 aggregates via bridging trifluoroacetates. (c) Coordination layer constructed by the chains and trans-1,3-bix ligands. (d) Packing of layer structures in 3A, which are linked by weak hydrogen bonds to give a three-dimensional supramolecular framework. All irrelevant hydrogen and fluorine atoms are omitted for clarity. Symmetry codes: A 1 − x, 1 − y, −z; B −x, 1 − y, −z; B −x, 1 − y, −z; C 1 + x, −1 + y, z; D −x, 2 − y, −z.
and 2B exhibit similar ladder structures constructed by the silver(I) chains and trans-1,4-bix ligands. The Ag···Ag separation by trans-1,4-bix of ca. 14.841 Å in 2B is very close to that found in 2A (14.814 Å). The silver(I) chain of 2B is also stabilized by three continuous face-to-face π−π interactions (intercentroid distances (I)···(II) 3.895 Å and (II)···(III) 4.054 Å) from three 4-methylphenylethynides. Nevertheless, a small difference exists for the two compounds. In 2B, each ethynide group is bounded to a square-pyramidal Ag5 basket, whereas the ethynide moiety C15C16 in 2A is capped by a butterfly-
As shown in Figure 3d, the infinite ladders are interconnected by two types of weak hydrogen bonds, that is, C51B−H51A···F1 (C51B···F1 3.460 Å) and C19C−H19A···F9 (C19C···F9 3.142 Å), to form a three-dimensional supramolecular structure. To explore the influence of varying the substituted group of phenylethynide on the structures of silver(I) aggregates and the resulting network, we subsequently replaced AgCCPh in 2A with AgCCC6H4Me-4 to achieve a nearly isostructural complex 2B (Figure S1, Supporting Information). Both 2A 2996
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Figure 5. (a) Coordination modes of the PhCC− ligands in 4 with atom labeling. Selected bond lengths [Å]: C1C2 1.221(11), C9C10 1.215(10), Ag···Ag 2.9025(10)−3.1849(10). (b) Characteristic cationic silver(I) chain in 4 formed from the linkage of Ag6 aggregates via bridging atoms Ag3 and Ag4. (c) Layer structure constructed by the flexible bbi-1 ligands and the neighboring silver(I) chains in the ab plane. (d) Threedimensional coordination framework constructed by the bbi ligands and the neighboring silver(I) chains. Hydrogen-bonding interactions that contribute to stabilization are indicated by broken lines. All irrelevant hydrogen and fluorine atoms are omitted for clarity. Symmetry codes: A 1 − x, 1 − y, 1 − z; B 1 − x, −y, 1 − z; C 1 + x, y, z; D 1 − x, −y, 2 − z; E −x, 1 − y, 1 − z.
shaped Ag4 basket. In addition, the hydrogen-bonding interactions in 2A and 2B are slightly different because of the introduction of the methyl groups of the 4-methylphenylethynides (Figure S1d, Supporting Information). In 2B, the methyl groups of the 4-methylphenylethynides are involved in the C− H···F interactions. As shown in Figure S1d, the ladders based on silver(I) chains and trans-1,4-bix ligands are interconnected by two kinds of weak hydrogen bonds, C9C−H9B···F17 (C9C···F17 3.169 Å) and C54F−H54A···F16E (C54C···F16E 3.495 Å), to produce a three-dimensional supramolecular structure (Figure S1d). [(AgCCPh)(AgO 2 CCF 3 ) 3 (trans-1,3-bix)(H 2 O)]·0.5H 2 O (3A), [(AgCCC6H4Me-4)(AgO2CCF3)3(trans-1,3-bix)(H2O)] (3B), [(AgCCC6H4Me-4)(AgO2CCF3)3(bbi)(H2O)] (3C), and [(AgCCC6H4tBu-4)(AgO2CCF3)3(trans-1,4-bix)] (3D). To evaluate the influence of the positions of the isomeric 1,n-bix ligands on the structures of silver(I) aggregates and the final network, a structurally different complex 3A was synthesized by using 1,3-bix instead of 1,4-bix in a similar manner to 2A. In the
crystal structure of 3A, the ethynide group composed of C1 and C2 adopts a μ5-η1,η1,η1,η2,η2 coordination mode and is surrounded by Ag1, Ag2, Ag3, Ag4, and Ag4A to give a square-pyramidal Ag5 basket with three Ag···C σ/π bonds (Ag3···C1 = 2.313(6) Å, Ag4···C1 = 2.469(6) Å, and Ag4A··· C1 = 2.439(6) Å), three Ag···C π bonds (Ag1···C1 = 2.355(6) Å, Ag1···C2 = 2.598(7) Å, and Ag3···C2 = 2.709(7) Å), and a Ag···C σ bond (Ag2···C1 = 2.135(7) Å) (Figure 4a). With an inversion center located at the center of the Ag4···Ag4A bond, two Ag5 baskets share an edge to engender a Ag8 aggregate. Two adjacent Ag8 aggregates are linked by two trifluoroacetate groups (O3−O4 and O3B−O4B) via μ3-O,O′,O″ coordination modes to yield an infinite chain (Figure 4b). The other four trifluoroacetate groups are all bonded to one Ag···Ag edge of two Ag5 baskets by the μ2-O,O′ modes, and the four imidazol1-ylmethyl groups of the trans-1,3-bix ligands coordinate to different silver(I) atoms. In this way, adjacent chains are linked by the trans-1,3-bix ligands to give a layer, with the Ag−N bond lengths in the range of 2.126(6)−2.203(6) Å (Figure 4c). In 2997
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Figure 6. (a) Coordination modes of the tBuCC− ligands in 5 with atom labeling. Selected bond lengths [Å]: C1C2 1.233(11), C7C8 1.203(11), Ag···Ag 2.8605(14)−3.1683(11). (b) Characteristic cationic silver(I) chain in 5 formed from the linkage of Ag8 and Ag6 aggregates via bridging atoms Ag1 and Ag3. (c) Layer structure constructed by the flexible bbi-3 ligands and the neighboring silver(I) chains in the bc plane. (d) Three-dimensional coordination framework constructed by the bbi ligands and neighboring silver(I) chains viewed along the c axis. Hydrogenbonding interactions that contribute to stabilization are indicated by broken lines. All irrelevant hydrogen and fluorine atoms are omitted for clarity. Symmetry codes: A − x, 1 − y, 1 − z; B x, 1 − y, −z; C −x, 1 − y, −z.
3A, the Ag···Ag separation by the trans-1,3-bix is ca. 14.808 Å, which is very near to the ones observed in 2A (ca. 14.860 Å) and 2B (ca. 14.814 Å). As shown in Figure 4d, adjacent layers are interconnected by two types of relatively weak C25D−H25A···O1 (C25D···O1 3.475 Å) and C24C−H24···O6 (C24C···O6 3.350 Å) hydrogen bonds to give a three-dimensional supramolecular architecture. To investigate the effect of varying the substituted group of phenylethynide on the structures of silver(I) aggregates and the resulting network, we subsequently replaced AgCCPh in 3A with AgCCC6H4Me-4 to afford a nearly isostructural layer complex 3B (Figure S2, Supporting Information). The Ag···Ag distance bridged by trans-1,3-bix of ca.14.845 Å in 3B is very close to the one found in 3A (ca. 14.808 Å). The result further indicates that the introduction of the methyl group of the phenylethynide did not influence the layer structure of the complex. However, the hydrogen-bonding interactions are slightly different between 3A and 3B because of the introduction of the methyl moiety of the phenylethynide. In
3B, there exist both weak C11−H11B···O6C (C11···O6C 3.354 Å) and C14−H14···F3B (C14···F3B 3.343 Å) hydrogen bonds between adjacent coordination layers, thus generating a three-dimensional supramolecular architecture (Figure S2d, Supporting Information). In contrast to complex 3B, complex 3C was synthesized by varying the spacers of the bis(imidazole) ligands. Although the spacers of the bis(imidazole) ligands differ greatly, the resulting complex 3C still shows the similar Ag8-based layer structure to those of both 3A and 3B (Figure S3, Supporting Information). Nevertheless, the Ag···Ag separation by the bbi ligand of ca. 12.916 Å in 3C is much shorter than those found in both 3A (ca. 14.808 Å) and 3B (ca.14.845 Å), resulting from the variation of the spacers of their bis(imidazole) ligands. Similar to 3A, weak hydrogen bonds C23B−H23···O4 (C23B···O4 3.299 Å) and C22B−H18···O5 (C22B···O5 3.390 Å) between the bbi and the trifluoroacetate occur between adjacent coordination layers, yielding a three-dimensional supramolecular architecture (Figure S3d, Supporting Information). 2998
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[(AgCCtBu)2(AgO2CCF3)4(bbi)] (5). Replacing AgCCPh by tBuCCAg as a reactant under similar reaction conditions as those for 4, a different complex 5 was obtained. The crystal structure of 5 contains two independent tert-butylethynide anions that exhibit different coordination modes. The ethynide moiety C1C2 in a μ5-η1,η1,η1,η2,η2 coordination mode inserts into a basket-like Ag5 unit to generate three Ag···C σ/π-type bonds (Ag5···C1 = 2.417(8) Å, Ag6···C1 = 2.368(7) Å, and Ag6B···C1 = 2.735(8) Å), three Ag···C π bonds (Ag1···C1 = 2.483(7) Å, Ag1···C2 = 2.632(7) Å, and Ag5···C2 = 2.750(7) Å), and a Ag···C σ-type bond (Ag5···C1 = 2.417(8) Å), whereas the ethynide moiety C7C8 is attached to a butterflyshaped Ag4 basket in a μ4-η1,η1,η1,η2 coordination mode through three Ag···C σ/π bonds (Ag1···C7 = 2.366(7) Å, Ag4···C7 = 2.717(9) Å, and Ag4A···C7 = 2.352(7) Å), a Ag···C π bond (Ag1···C8 = 2.661(8) Å), and a Ag···C σ-type bond (Ag2···C7 = 2.081(8) Å) (Figure 6a). The dihedral angle of the wings Ag1Ag2Ag4 and Ag2Ag4Ag4A is 64.30°. Two inversionrelated Ag5 baskets share an edge to produce a Ag8 aggregate, whereas linkage of a pair of inversion-related Ag4 baskets sharing a common edge results in a Ag6 aggregate. Further, adjacent Ag8 and Ag6 aggregates are fused together through two shared silver(I) atoms (Ag1 and Ag3) to yield an infinite silver(I) chain, as shown in Figure 6b. The trifluoroacetate anions as effective counteranions chelate to the silver(I) chain, in μ2-O,O′ and μ3-O,O′,O″ coordination modes, respectively. Different from those in 4, the two bbi ligands in 5 show TTT and GTG conformations, respectively. The bbi ligands containing the nitrogen atoms labeled N1 and N3 are designated as bbi-3 and bbi-4, respectively. The flexible bbi-3 exhibits a TTT conformation, connecting the neighboring silver(I) chains to form a coordination layer structure in the bc plane, with the Ag−N bond length of 2.123(7) Å (Figure 6c). Adjacent layers are further linked by the bbi-4 ligands in GTG conformations to generate a three-dimensional framework (Figure 6d), with the Ag−N distance of 2.097(7) Å. The Ag··· Ag distances spanned by bbi-3 and bbi-4 are 12.991(2) and 12.088(1) Å, respectively, which may be generated from the different conformations of the two bbi ligands in 5. Further, the three-dimensional framework of 5 is stabilized by C22−H22··· F5A (C22···F5A 3.476 Å), C29−H29A···F4A (C29···F4A 3.527 Å), and C30−H30A···F10C (C30···F10C 3.420 Å) hydrogenbonding interactions (Figure 6d). It is noteworthy that compounds 4 and 5 demonstrate effects of the substituted groups of the ethynides. By varying the substituted group from phenyl to tert-butyl, an obvious change in the structures of silver(I) aggregates and the resulting framework was observed between 4 and 5. For instance, in 4, two inversion-related Ag4 baskets share an edge to produce a Ag6 aggregate, which are further fused together through two shared silver(I) atoms to yield an infinite silver(I) chain. However, in 5, two inversion-related Ag5 baskets and a pair of inversion-related Ag4 baskets form Ag8 and Ag6 aggregates, respectively, wherein adjacent Ag8 and Ag6 aggregates are further held together through two shared silver(I) atoms to form an infinite silver(I) chain. In addition, each bbi ligand in 4 shows a GTG conformation, whereas the two bbi ligands in 5 adopt GTG and TTT conformations, respectively, which may be attributed to the variation of the substituted groups of the ethynides. Finally, the bbi ligands in different conformations bridge the silver(I) chains to yield the three-dimensional frameworks of 4 and 5 with distinct structural patterns.
Complex 3D was obtained by varying the substituted groups of phenylethynides from methyl to tert-butyl and the flexible bis(imidazole) ligands from bbi to 1,4-bix under similar reaction conditions as those for 3C. Although 3D exhibits a Ag8-based layer structure similar to those of 3A−3C, the coordination environment of the ethynide and the type of the hydrogen-bonding interactions in 3D are entirely different from those in 3A−3C (Figure S4, Supporting Information). In 3A− 3C, each ethynide group is bound to the square-pyramidal Ag5 basket in the μ5-η1,η1,η1,η2,η2 coordination mode, whereas each ethynide group adopts the μ5-η1,η1,η1,η1,η2 coordination mode in 3D (Figure S4). Noteworthy, the methyl groups of the phenylethynides were introduced into the 3B and 3C, but they were not involved in the hydrogen-bonding interactions during the formation of the final three-dimensional supramolecular architectures. However, the tert-butyl group participates in C10−H10C···F7B (C10···F7B 3.311 Å) hydrogen-bonding interaction in 3D, leading to a three-dimensional supramolecular architecture (Figure S4d, Supporting Information). [(AgCCPh)2(AgO2CCF3)4(bbi)(H2O)]·2H2O (4). To investigate the influence of the spacers of the flexible bis(imidazole) ligands on the framework structures, the bis(imidazole) ligand bbi with a flexible −CH2− spacer was used under the similar reaction conditions to 1A, and a new compound 4 was obtained. In the crystal structure of 4, there are two independent phenylethynide anions taking two different coordination modes. The ethynide moiety C1C2 is embraced by a butterfly-shaped Ag4 basket in a μ4-η1,η1,η1,η2 mode through three Ag···C σ/π bonds (Ag3···C1 = 2.397(7) Å, Ag1···C1 = 2.595(7) Å, and Ag1B···C1 = 2.374(7) Å), a Ag···C π bond (Ag1B···C2 = 2.771(9) Å), and a Ag···C σ bond (Ag2··· C1 = 2.052(7) Å) (Figure 5a). The remaining ethynide terminal, C9C10, is also bound to a butterfly-shaped Ag4 basket in a μ4-η1,η1,η2,η2 mode, with two Ag···C σ/π bonds (Ag3···C9 = 2.442(6) Å and Ag5···C9 = 2.347(7) Å), three Ag···C π bonds (Ag3···C10 = 2.821(7) Å, Ag6A···C9 = 2.347(7) Å, and Ag6A···C10 = 2.605(7) Å), and a Ag···C σ bond (Ag4···C9 = 2.095(7) Å). Notably, two inversion-related Ag4 baskets share an edge to produce a Ag6 aggregate. As shown in Figure 5b, two types of Ag6 aggregates are further fused together through two shared silver(I) atoms (Ag3 and Ag4) to generate an infinite silver(I) chain. The trifluoroacetate anions adopt μ2-O,O′ coordination modes to act as effective counteranions to balance the charges. There exist two crystallographically different bbi ligands in the crystal structure of 4. For convenience, the bbi molecules containing the nitrogen atoms labeled N1 and N3 are designated as bbi-1 and bbi-2, respectively. The flexible bbi-1 ligands bridge the neighboring silver(I) chains in GTG conformations (G = gauche and T = trans) to form a layer structure in the ab plane (Figure 5c), with the Ag−N distance of 2.127(6) Å. The Ag··· Ag separation spanned by bbi-1 of 12.590(1) Å is slightly shorter than that in the related compound 3C (ca. 12.916 Å). Further, adjacent layers are linked by the bbi-2 ligands in GTG conformations to give rise to a three-dimensional framework (Figure 5d), with the Ag−N distance of 2.113(6) Å, in which an infinite channel partially filled with water molecules is found. The Ag···Ag distance linked by the bbi-2 of 11.948(1) Å is shorter than that spanned by bbi-1 (12.590(1) Å). As shown in Figure 5d, the three-dimensional coordination framework is further stabilized by C19−H19···F4C (C19···F4C 3.438 Å), C6−H6···F5D (C6···F5D 3.341 Å), and C15−H15···F2E (C15···F2E 3.434 Å) hydrogen-bonding interactions. 2999
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Ancillary Role of Flexible Bis(imidazole) Ligand in Coordination Framework Assembly. In crystalline complexes 1A−5, the bis(imidazole) spacer ligands were successfully introduced into the silver(I)−ethynide system for the first time, which enriches its structural diversity. The X-ray analysis results showed that the spacer length and conformation of the flexible bis(imidazole) ligands can influence the assembly of silver(I) aggregates to give the resulting coordination network. In 2A and 3A, although both 1,3-bix and 1,4-bix adopt the trans-conformation, their structures are entirely different because of variation of the positions of the two imidazol-1ylmethyl groups on their phenyl rings. In 2A, adjacent silver(I) chains are linked by the trans-1,3-bix ligands to form an infinite ladder, whereas a different layer structure is found for 3A. A similar influence of the disposition of the pair of imidazol-1ylmethyl groups on the resulting crystal structures is also supported by comparing compounds 2B and 3B. On the other hand, the effect of separation of the two imidazole groups by variable spacers is clearly shown by comparing compounds 4 with 1A, 2A, or 3A. In contrast to the 1,2-, 1,3-, and 1,4-bix ligands, the bbi ligand has a more flexible 1,4-butanediyl spacer. When the 1,2-, 1,3-, and 1,4-bix ligands were introduced into the silver(I)−phenylethynide system, the infinite chain, ladder, and layer structures were produced in 1A, 2A, and 3A, respectively. Nevertheless, in 4, the bbi ligands in the GTG conformation bridge infinite silver(I)−phenylethynide chains to yield a three-dimensional coordination framework. Role of Substituted Group on Ethynide in Coordination Framework Assembly. Variation of the substituted group on the ethynide results in structural modification of the silver(I) aggregates and resulting network. For instance, an obvious structural change was observed between 4 and 5 by changing the substituted group from phenyl to tert-butyl. In 4, two inversion-related Ag4 baskets share an edge to produce a Ag6 aggregate; however, in 5, two inversion-related Ag5 baskets and a pair of inversion-related Ag4 baskets form enlarged Ag8 and Ag6 aggregates, respectively. Furthermore, the structural patterns of 4 and 5 are also different. In 4, the bbi ligand shows a GTG conformation, whereas the two bbi ligands in 5 adopt GTG and TTT conformations, respectively. Finally, the independent bbi ligands bridge the silver(I) chains to yield distinct three-dimensional structural patterns of 4 and 5. In addition, the coordination framework also can be affected by the position and steric bulk of the substituents on the aromatic ring. For example, in 1B, the 1,3-bix ligands in a cisconformation are alternatively attached on both sides of a silver(I) chain. However, when the 2-MeC6H4CC− anion was replaced by the 4-MeC6H4CC− anion, a layer structure of 3B based on trans-1,3-bix ligands and silver(I) chains was produced under similar synthetic conditions. A similar effect of the position and steric bulk of the substituents on the complex structures was also supported by comparing 2B with 3D, and 3C with 4. Silver(I) Aggregation. Structure characterization of 1A−5 showed that the nuclearities of silver(I) aggregates therein vary within a broad range from 4 to 11. In 3A−3D, two Ag5 baskets share an edge to engender a discrete Ag8 aggregate, whereas, in 1A−2B, 4, and 5, adjacent silver(I) aggregates are joined together through argentophilic interactions to form silver(I) chains, which exhibit structural variation depending on specific ancillary bis(imidazole) and ethynide combinations. For example, when the 1,2-bix ligand in 1A was replaced by 1,4bix in 2A, different silver(I) chain structures are obtained. In
1A, adjacent Ag7 aggregates based on Ag4 and Ag5 baskets are fused together through two shared silver(I) atoms to yield a silver(I) chain, whereas the silver(I) chain in 2A is composed of Ag10 aggregates. This finding is also supported by comparing the silver(I) chain structures of 1A and 4. Different from the Ag7-based silver(I) chain in 1A, the silver(I) chain in 4 consists of Ag6 aggregates sharing two Ag4 baskets, which mainly arises from changing the bis(imidazole) ligands from 1,2-bix to bbi. On the other hand, different silver(I) chain structures were also found between 2A and 2B, and between 4 and 5, by altering the ethynide components. Complex 2A features a Ag10-based silver(I) chain, but a slightly different silver(I) chain constructed by Ag11 aggregates sharing three Ag5 baskets was obtained in 2B when AgCCPh employed in 2A was replaced with AgCCC6H4Me-4 in 2B. Similarly, a distinct silver(I) chain fused together by Ag8 and Ag6 aggregates was observed in 5 instead of Ag6-based species found in 4 after replacing AgC CPh by tBuCCAg.
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CONCLUSION In the present study, we report a new series of 10 silver(I) ethynide/trifluoroacetate mixed-ligand complexes that incorporate flexible bis(imidazole) moieties in the generation of various infinite ladder, layer, and three-dimensional coordination frameworks; in the ladder- and layer-type structures, the onset of weak intermolecular interactions results in the assembly of supramolecular networks. It is demonstrated that, using bix-type ligands as synthetic precursors in forming the present series of complexes, variation of the positions of the pair of imidazolylmethyl substituents on the aromatic ring plays a dominant role in coordination framework assembly.
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ASSOCIATED CONTENT
S Supporting Information *
X-ray crystallographic data and refinement parameters (Table S1) and selected bond lengths and angles (Table S2) for complexes 1A−5, and Figures S1−S4. This material is available free of charge via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We gratefully acknowledge financial support by the Hong Kong Research Grants Council (GRF CUHK 402710) and the Wei Lun Foundation, as well as The Chinese University of Hong Kong for the award of a Research Fellowship to J.Y. and a Postgraduate Studentship to T.H.
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