Ag(I) Complexes Generated from Double Schiff-Base Ligand with

with bipyridyl. Ezzatollah Najafi , Mostafa M. Amini , Mohammad Janghouri , Ezeddine Mohajerani , Seik Weng Ng. Inorganica Chimica Acta 2014 415, ...
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Ag(I) Complexes Generated from Double Schiff-Base Ligand with Thiazole as the Terminal Binding Sites Yu-Bin Dong,* Le Wang, Jian-Ping Ma, Xia-Xia Zhao, Da-Zhong Shen, and Ru-Qi Huang College of Chemistry, Chemical Engineering and Materials Science, Shandong Key Lab of Functional Chemical Materials, Shandong Normal UniVersity, Jinan, 250014, P. R. China

CRYSTAL GROWTH & DESIGN 2006 VOL. 6, NO. 11 2475-2485

ReceiVed March 22, 2006; ReVised Manuscript ReceiVed August 23, 2006

ABSTRACT: A double Schiff-base ligand 1,4-bis(2-thiazolyl)-2,3-diaza-1,3-butadiene (L8) has been synthesized, and its coordination chemistry with various silver salts AgX (X ) SbF6-, SO3CF3-, H2PO4-, and NO3-) has been investigated. The resulting molecular structures are delicately dependent on the nature of the counterions and the solvent intermedia. Uncoordinating counterions (X ) SbF6- and SO3CF3-) generated the hydrogen-bonded frameworks based on discrete molecular complex building blocks, whereas coordinating anions (X ) H2PO4- and NO3-) formed polymeric complexes driven by the metal-anion interactions. Furthermore, the luminescent and electrical conductive properties of some new complexes were investigated. Introduction During the past decade, pronounced interest has been focused on new discrete supramolecular complexes and coordination polymers based on polydentate organic ligands due to their novel structural topologies and potential applications in sensing, catalysis, ion exchange, separations, or gas storage.1-3 To date, various intriguing molecular frames have been designed and synthesized by the direct chemical combination of the selected basic components such as the coordination geometry of metal cations, the binding site of donating atoms, and the length and shape of spacers by the induction of weak intra- or/and intermolecular interactions. In addition, the features of counterions such as charge, size, geometry, and solvent templating effects imply that the polyatomic counterions and solvent intermedia play crucial roles in the self-assembly of functional molecular complexes, which was reflected by recent achievements in the function of anions and solvent intermedia in supramolecular chemistry.4 We have been exploring the metal-organic assemblies based on the double Schiff-base ligands.5 Our previous research demonstrated that such types of ligands are very useful to construct novel polymeric and discrete complexes due to their zigzag conformation of the spacer moiety (-RCdN-NdCR-) between the two terminal coordination groups. As shown in Scheme 1, pyridine, pyrazine, and quinoxaline diazene types of organic ligands have been used as the building blocks, but the exploitation of the ligands with two terminal five-membered heterocyclic rings such as the thiazole moiety has until recently remained unexplored. Pursuing our research in this area, we describe here the coordination chemistry of the double Schiffbase ligand 1,4-bis(2-thiazolyl)-2,3-diaza-1,3-butadiene (L8) with various silver salts AgX (X ) SO3CF3-, SbF6-, H2PO4-, and NO3-) and the luminescent and conductive properties of these new discrete and polymeric complexes (Scheme 1). Experimental Section Materials and Methods. AgSO3CF3, AgSbF6, AgH2PO4, AgNO3, and 2-acetylthiazole (Acros) were used as obtained without further purification. Infrared (IR) samples were prepared as KBr pellets, and spectra were obtained in the 400-4000 cm-1 range using a Perkin* To whom correspondence [email protected].

should

be

addressed.

E-mail:

Elmer 1600 FTIR spectrometer. Elemental analyses were performed on a Perkin-Elmer model 2400 analyzer. 1H NMR data were collected using an AM-300 spectrometer. Chemical shifts are reported in δ relative to TMS. All fluorescence measurements were carried out on a Cary Eclipse spectrofluorimeter (Varian, Australia) equipped with a xenon lamp and quartz carrier at room temperature. Thermogravimetric analyses were carried out using a TA Instrument SDT 2960 simultaneous DTA-TGA under flowing nitrogen at a heating rate of 10 °C/ min. Electrical conductivity and mass spectrometric measurements were performed on Agilent Technologies (4294A-ATO-20150) and Agilent 1100 LC-MSD, respectively. Synthesis of L8. 2-Acetylthiazole (1.27 g, 10 mmol) was dissolved in ethanol (30 mL), followed by dropwise addition of the hydrazine solution (85 wt. % solution in water, 0.22 g, 3.75 mmol). After two drops of formic acid were added, the mixture was stirred at room temperature for 48 h. After the solvent was removed under vacuum, the residue was extracted with methylene chloride and washed with water several times. The organic phase was dried over MgSO4, filtered, and, upon removal of the solvent, an analytically pure bright yellow crystalline solid was obtained in 97% yield. m.p. ) 120-122 °C. IR (KBr pellet cm-1): 3447(s), 3122(s), 1644(s), 1605(s), 1489(s), 1414(s), 1362(s), 1292(m), 1153(w), 1063(s), 950(m), 900(w), 875(w), 749(s), 642(s), 559(s), 486(m). 1H NMR (300 MHz, CDCl3, 25 °C, TMS, ppm): 7.91-7.92 (d, 2H, 2-C3H2NS), 7.45-7.46 (d, 2H, 2-C3H2NS), 2.53 (s, 6H, 2-CH3).1H NMR (300 MHz, DMSO, 25 °C, TMS, ppm): 7.99-8.00 (d, 2H, 2-C3H2NS), 7.91-7.92 (d, 2H, 2-C3H2NS), 2.402.41(s, 6H, 2-CH3). Elemental analysis (%) calcd. For C10H10N4S2: C 48.0, H 4.0, N 22.4; Found: C 47.6, H 4.3, N 22.5. Synthesis of 1. A THF solution (8 mL) of AgSbF6 (34.4 mg, 0.1 mmol) was slowly diffused into a CH2Cl2 solution (8 mL) of L8 (25.0 mg, 0.1 mmol). Yellow crystals formed in about 2 days in 90% yield. IR (cm-1, KBr pellet): 3415(m), 3123(m), 3078(m), 2926(w), 1793(w), 1604(s), 1488(s), 1410(s), 1365(s), 1291(s), 1275(s), 1174(s), 1090(s), 1064(s), 953(m), 889(s), 739(s), 664(vs), 558(s), 508(w). 1HNMR (300 MHz, DMSO, 25 °C, TMS, ppm): 8.07-8.08 (d, 2H, 2-C3H2NS), 7.98-7.99 (d, 2H, 2-C3H2NS), 3.67 (t, 4H, C4H8O), 3.00(s, 6H, 2-CH3), 1.82 (t, 4H, C4H8O). Elemental analysis (%) Caled. for C11H12AgCl2F6N4S2Sb: C 25.23, H 2.70, N 8.41; Found: C 25.21, H 2.68, N 8.40. Synthesis of 2. A toluene solution (8 mL) of AgSbF6 (34.4 mg, 0.1 mmol) was slowly diffused into a CH2Cl2 solution (5 mL) of L8 (25.0 mg, 0.1 mmol). Yellow crystals formed in about one week in 41% yield. IR (cm-1, KBr pellet): 3435(m), 3131(m), 3062(m), 2932(w), 1809(w), 1611(s), 1492(s), 1415(s), 1374(s), 1293(s), 1279(s), 1188(s), 1099(s), 1067(s), 958(m), 891(s), 742(s), 667(vs), 569(s), 512(w). Elemental analysis (%) Caled. for C11H12AgCl2F6N4S2Sb C 19.44, H 1.77, N 8.25; Found: C 19.18, H 1.82, N 8.44. Synthesis of 3. A THF solution (8 mL) of AgSO3CF3 (25.7 mg, 0.1 mmol) was slowly diffused into a CH2Cl2 solution (8 mL) of L8 (25.0 mg, 0.1 mmol). Yellow crystals formed in about one week in 96% yield. IR (cm-1, KBr pellet): 3463(w), 3111(m), 3091(m), 2924(w),

10.1021/cg060158g CCC: $33.50 © 2006 American Chemical Society Published on Web 10/12/2006

2476 Crystal Growth & Design, Vol. 6, No. 11, 2006 Scheme 1.

Dong et al.

Double Schiff-Base Ligands Used in the Construction of Polymeric Metal-Organic Complexes

Table 1. Crystallographic Data for 1-5a

empirical formula fw cryst syst a (Å) b (Å) c (Å) R (°) β (°) γ (°) V (Å3) space group Z value F calc (g/cm3) µ (Mo KR) (mm-1) temp (K) no. of obsns (I > 3σ) final R indices [I>2σ(I)]: R; Rw a

1

2

3

4

5

C14H18AgF6N4OS2Sb 666.06 monoclinic 14.381(6) 9.979(4) 16.373(7)

C11H10AgF3N4O3S3 507.28 trigonal 13.0440(19) 13.0440(19) 18.275(4) 90 90 120 2692.8(8) P3hc1 6 1.877 1.519

C10H14Ag2N4O8P2S2 660.05 monoclinic 20.934(6) 9.529(3) 10.578(3)

C10H10Ag2N6O6S2 590.10 monoclinic 20.606(9) 9.489(4) 9.697(4)

115.762(4)

117.339(5)

2193.7(17) P2/c 4 2.017 2.377

C11H12AgCl2F6N4S2Sb 678.89 orthorhombic 17.353(9 20.233(10) 18.235(9) 90 90 90 6402(6) Pna2(1) 12 2.113 2.684

1900.4(10) C2/c 4 2.307 2.498

1684.2(13) C2/c 4 2.327 2.617

298(2) 3987

298(2) 11079

298(2) 1981

298(2) 1684

298(2) 1490

0.0620; 0.1569

0.0578; 0.1310

0.0519; 0.1432

0.0871; 0.2105

0.0388; 0.0961

110.993(6)

R1 ) ∑||Fo| - |Fc||/∑|Fo|. wR2 ) {∑[w(Fo2 - Fc2)2]/∑[w(Fo2)2] }1/2.

Scheme 2.

Synthesis of New Ligand L8 and Its Ag(I) Coordination Polymers

1604(s), 1489(s), 1406(s), 1365(m), 1258(s), 1161(s), 1090(m), 1031(s), 954(w), 913(w), 890(m), 770(s), 736(s), 638(s), 557(m), 515(m). 1 HNMR (300 MHz, DMSO, 25 °C, TMS, ppm): 7.99-7.80 (d, 2H, 2-C3H2NS), 7.90-7.92 (d, 2H, 2-C3H2NS), 2.41 (s, 6H, 2-CH3). Elemental analysis(%) Caled. for C11H10AgF3N4O3S3: C 23.67, H 1.97, N 11.05; Found: C 23.61, H 1.98, N 11.02. Synthesis of 4. A toluene solution (8 mL) of AgH2PO4 (20.5 mg, 0.1 mmol) was slowly diffused into a CH2Cl2 solution (8 mL) of L8 (25.0 mg, 0.1 mmol). Yellow crystals formed in about one week in 41% yield. IR (cm-1, KBr pellet): 3452(w), 3075(s), 2923(m), 1611(s), 1548(s), 1487(s), 1407(s), 1297(s), 1143(s), 1081(s), 983(s), 915(s), 832(m), 804(s), 736(s), 678(s), 582(m), 507(m), 454(m). Anal. Calcd for C10H14Ag2N4O8P2S2: C 18.18, H 1.52, N 8.48; Found: C 18.15, H 1.50, N 8.43. Synthesis of 5. A THF solution (8 mL) of AgNO3 (17.0 mg, 0.1 mmol) was slowly diffused into a CH2Cl2 solution (8 mL) of L8 (25.0

mg, 0.1 mmol). Yellow crystals formed in about one week in 50% yield. IR (cm-1, KBr pellet): 3420(s), 3109(m), 1649(m), 1605(s), 1486(s), 1384(vs), 1320(s), 1295(s), 1151(s), 1078(s), 952(w), 908(w), 877(w), 822(w), 770(s), 736(s), 686(m), 641(m), 554(m). Elemental analysis (%) Caled. for C10H10Ag2N6O6S2: C 20.34, H 1.69, N 14.23; Found: C 20.08, H 1.38, N 13.99. Single-Crystal Structure Determination. Suitable single crystals of 1-5 were selected and mounted in air onto thin glass fibers. X-ray intensity data were measured at 298(2) K on a Bruker SMART APEX CCD-based diffractometer (Mo KR radiation, λ ) 0.71073 Å). The raw frame data for 1-5 were integrated into SHELX-format reflection files and corrected for Lorentz and polarization effects using SAINT.6 Corrections for incident and diffracted beam absorption effects were applied using SADABS.6 None of the crystals showed evidence of crystal decay during data collection. All structures were solved by a combination of direct methods and difference Fourier syntheses and

Ag(I) Complexes from Double Schiff-Base Ligand

Crystal Growth & Design, Vol. 6, No. 11, 2006 2477

Table 2. Interatomic Distances (Å) and Bond Angles (°) with esds (in parentheses) for 1 Ag(1)-N(4)#1 Ag(1)-N(2)

2.184(5) 2.560(5)

Ag(1)-N(1) Ag(1)-N(3)#1

N(4)#1-Ag(1)-N(1) N(1)-Ag(1)-N(2) N(1)-Ag(1)-N(3)#1

151.63(16) N(4)#1-Ag(1)-N(2) 70.02(16) N(4)#1-Ag(1)-N(3)#1 134.48(16) N(2)-Ag(1)-N(3)#1

2.204(5) 2.627(5) 35.65(16) 69.40(15) 84.83(16)

a Symmetry transformations used to generate equivalent atoms: #1 -x + 1, y, -z + 1/2. #2 -x, y, -z + 1/2.

Table 5. Interatomic Distances (Å) and Bond Angles (°) with Esds (in parentheses) for 4 Ag(1)-N(1) Ag(1)-O(1)#1 Ag(1)-Ag(1)#1

2.274(9) Ag(1)-O(1) 2.402(9) Ag(1)-N(2) 3.357(2)

2.366(9) 2.571(11)

N(1)-Ag(1)-O(1) O(1)-Ag(1)-O(1)#1 O(1)-Ag(1)-N(2) N(1)-Ag(1)-Ag(1)#1 O(1)#1-Ag(1)-Ag(1)#1

154.3(3) 90.5(3) 102.3(3) 160.0(2) 44.8(2)

115.2(3) 69.3(3) 111.2(3) 45.7(2) 114.1(2)

N(1)-Ag(1)-O(1)#1 N(1)-Ag(1)-N(2) O(1)#1-Ag(1)-N(2) O(1)-Ag(1)-Ag(1)#1 N(2)-Ag(1)-Ag(1)#1

Table 3. Interatomic Distances (Å) and Bond Angles (°) with esds (in parentheses) for 2

a Symmetry transformations used to generate equivalent atoms: #1 -x + 1, -y, -z + 1. #2 -x + 1, y, -z + 3/2.

Ag(1)-N(7) Ag(1)-N(9) Ag(2)-N(4) Ag(2)-N(5) Ag(3)-N(11) Ag(3)-N(10)

2.181(9) 2.522(10) 2.158(9) 2.510(11) 2.197(10) 2.532(11)

Ag(1)-N(8) Ag(1)-N(6) Ag(2)-N(3) Ag(2)-N(2) Ag(3)-N(12) Ag(3)-N(1)

2.227(9) 2.619(9) 2.208(8) 2.520(10) 2.201(10) 2.546(8)

N(7)-Ag(1)-N(8) N(8)-Ag(1)-N(9) N(8)-Ag(1)-N(6) N(4)-Ag(2)-N(3) N(3)-Ag(2)-N(5) N(3)-Ag(2)-N(2) N(11)-Ag(3)-N(12) N(12)-Ag(3)-N(10) N(12)-Ag(3)-N(1)

155.1(3) 71.2(3) 113.1(3) 155.1(4) 113.1(3) 72.7(3) 150.4(4) 121.1(3) 72.8(3)

N(7)-Ag(1)-N(9) N(7)-Ag(1)-N(6) N(9)-Ag(1)-N(6) N(4)-Ag(2)-N(5) N(4)-Ag(2)-N(2) N(5)-Ag(2)-N(2) N(11)-Ag(3)-N(10) N(11)-Ag(3)-N(1) N(10)-Ag(3)-N(1)

127.8(3) 71.6(3) 124.7(3) 72.7(3) 127.4(3) 118.1(3) 71.9(3) 128.9(3) 114.6(2)

complex of formula [Ag2L82]SbF6‚(THF). 1 is not soluble in water and common organic solvents but soluble in CH3CN and DMSO to some extent. The electrospray (ES) mass spectrum shows peaks at m/z ) 357 and 359, which corresponds to the formation of [Ag2L82]2+ species in solution. Compound 1 was found to crystallize in the space group monoclinic, P2/c. Crystallographic data for 1 are shown in Table 1. Selected bond lengths and angles are shown in Table 5. X-ray single-crystal analysis revealed that each Ag(I) ion lies in a distorted tetrahedral coordination environment which consists of two thiazole N-donors and two Schiff-base N-donors from two L8 ligands, respectively. Thus, the L8 ligand herein is fourcoordinated and binds two silver cations through two pair of chelating N-donors in the middle into a chiral double-helical dimer with the Ag‚‚‚Ag distance of 5.1 Å (Figure 1). As shown in Figure 1, the ligand is badly twisted, which is reflected by the large dihedral angle (86.61°) between the two terminal thiazole planes. 1 contains equal amounts of the two enantiomers (Figure 2). Interestingly, two enantiomers are connected to each other by three sets of F‚‚‚H-C hydrogen bonds,7 respectively, into two-dimensional (2D) chiral nets with opposite chirality (Figure 3). As indicated in Figure 4, these 2D chiral layers are extended parallel to the crystallographic ac plane and stacked alternatively along the crystallographic b axis to generate parallelogram-like channels, in which the THF solvent molecules are located as the guest (Figure 5). Compound [Ag(L8)SbF6]‚CH2Cl2 (2) was prepared in 90% yield following the same procedure as that for 1 but using the toluene/CH2Cl2 mixed solvent system instead of the THF/CH2Cl2 mixed solvent system. The X-ray single-crystal analysis revealed that 2 crystallizes in the orthorhombic space Pna2(1). It is different from 1, and 2 exists as a trimer and possesses a trinuclear circular triple-helical structure. As indicated in Figure

Table 4. Interatomic Distances (Å) and Bond Angles (°) with esds (in parentheses) for 3a Ag(1)-N(2)#1 N(2)#1-Ag(1)-N(2) N(2)-Ag(1)-N(1) N(2)-Ag(1)-N(1)#1

2.240(3) 138.41(18) 72.17(12) 130.18(12)

Ag(1)-N(2) N(2)#1-Ag(1)-N(1) N(2)#1-Ag(1)-N(1)#1 N(1)-Ag(1)-N(1)#1

2.240(3) 130.18(12) 72.17(12) 122.96(15)

a Symmetry transformations used to generate equivalent atoms: #1 -x + 2,-x + y + 1,-z + 1/2. #2 x - y, -y, -z + 1/2. #3 -y + 1, x - y, z. #4 -x + y + 1, -x + 1, z. #5 -x + y, -x, z. #6 -y, x - y, z. #7 -x, -y, -z + 1.

refined against F2 by the full-matrix least squares technique. Crystal data, data collection parameters, and refinement statistics for 1-5 are listed in Table 1. Relevant interatomic bond distances and bond angles for 1-5 are given in Tables 2-6.

Results and Discussion Structural Analysis of 1 and 2. Treatment of AgSbF6 with 1 equiv of L8 in a THF/CH2Cl2 mixed solvent system afforded 1 as yellow crystals in 40% yield (Scheme 2). Compound 1 gave elemental analysis consistent with a dinuclear molecular

Figure 1. The ORTEP figure (left) and space-filling model (right) of 1. Two strands are colored as green and blue, respectively.

2478 Crystal Growth & Design, Vol. 6, No. 11, 2006

Dong et al.

Figure 2. Enantiomers presented in 1.

Figure 3. 2D hydrogen-bonded nets with opposite chirality. dF(3)‚‚‚H(2) ) 2.705(5) Å, dF(3)‚‚‚H(9) ) 2.697(5) Å, dF(7)‚‚‚H(11) ) 2.795(5) Å; dF(3)‚‚‚C(2) ) 3.4 Å, dF(3)‚‚‚C(9) ) 3.4 Å, dF(7)‚‚‚C(11) ) 3.2 Å; < F(3)‚‚‚H(2)-C(2) ) 143°, < F(3)‚‚‚H(9)-C(9) ) 141°, < F(3)‚‚‚H(11)C(11) ) 113°.

Figure 4. Side view of the chiral nets stacking (space-filling model). Two opposite chiral nets are colored as deep-yellow and blue, respectively. THF molecules are omitted for clarity.

Figure 5. Crystal packing of 1.

6, there are three types of crystallographically independent Ag(I) ions in 2, each again lying in a distorted tetrahedral coordination environment defined by the two thiazole N-donors and two Schiff-base N-donors provided by three four-coordinated L8 ligands, respectively. The dihedral angle between two terminal thiazole rings is 52.54°, which is smaller than that of 1. Consistent with this intraligand twisting, the compound exhibits a triple-helical [Ag3L83]3+ crown-like trimer, in which three Ag(I) atoms form an nonequilateral triangle with Ag‚‚‚Ag

distances of 5.5, 5.4, and 5.2 Å, respectively. The dimensions of the crown (i.e., the distances between the thiazole S atoms on the same side of the trisilver plane) are 6.7, 7.5, and 8.0 Å, respectively, and the shortest distance between Ag(I) and S atoms on the same side is 4.5 Å. It is worth pointing out that, in 2, there are two sets of crown complexes that are oriented in different directions in the solid state. Four neighboring [Ag3L83]3+ units, two with the same orientation, surround one of three SbF6anions to generate a cavity (Figure 7). Additionally, very complicated hydrogen-bonding systems are present in 2. As shown in Figure 7, three and four SbF6- anions are located above and below the crown, respectively, and hydrogen bonded to the [Ag3L83]3+ unit through weak F‚‚‚H-C bonds.7 In the solid state, 2 consists of an infinite three-dimensional (3D) hydrogen-bonded network in which [Ag3L83]3+ subunits are connected to each other through SbF6- nodes. The Sb(2)F6anion and methylene chloride solvent molecules fill in the channels extended along the crystallographic b axis (Figure 8). Compound 2 is air stable. The thermogravimetric analyses trace of 2 show that the methylene chloride molecules are lost from 50 to 110 °C and the framework of 2 is stable up to 230 °C. The electrospray (ES) mass spectrum shows a peak at m/z ) 357 and 359, which corresponds to the formation of [Ag3L83]3+ species in DMSO.

Ag(I) Complexes from Double Schiff-Base Ligand

Crystal Growth & Design, Vol. 6, No. 11, 2006 2479

Figure 6. The ORTEP figure (left) and space-filling model (right) of 2. Three strands are colored as green, blue and red, respectively.

Figure 7. Four neighboring M3L3 crowns getting together to form cavity, in which one SbF6- is located (left, two sets of crown units are colored as different colors for clarity); hydrogen-bonding systems found in 2 (right). dF(13)‚‚‚H(21) ) 2.712(5) Å, dF(15)‚‚‚H(9) ) 2.463(5) Å, dF(1)‚‚ ‚H(19) ) 2.699(5) Å, dF(14)‚‚‚H(30) ) 2.531(5) Å, dF(2)‚‚‚H(12) ) 2.413(5) Å, dF(8)‚‚‚H(12) ) 2.673(5) Å, dF(10)‚‚‚H(11) ) 2.498(5) Å, dF(13)‚‚‚H(1) ) 2.365(5) Å; dF(13)‚‚‚C(21) ) 3.6 Å, dF(15)‚‚‚C(9) ) 3.3 Å, dF(1)‚‚‚C(19) ) 3.4 Å, dF(14)‚‚‚C(30) ) 3.2 Å, dF(2)‚‚‚C(12) ) 3.0 Å, dF(8)‚‚‚C(12) ) 3.4 Å, dF(10)‚‚‚C(11) ) 3.3 Å, dF(13)‚‚‚C(1) ) 3.1 Å;