Polyhedron 20 (2001) 3165–3170

Two silver(I)–thiolate polymers with zigzag chain and lamellarstructures

Rui-Hu Wang, Mao-Chun Hong *, Wei-Ping Su, Yu-Cang Liang, Rong Cao,Ying-Jun Zhao, Jia-Bao Weng

State Key Laboratory of Structural Chemistry, Fujian Institute of the Research on the Structure of Matter, Chinese Academy of Sciences,Fuzhou, Fujian 350002, China

Received 18 May 2001; accepted 22 August 2001

Abstract

Two novel Ag(I) coordination polymers containing organosulfur ligands, [Ag2(bmpb)(NO3)2]n (1) and [{Ag5(bpsq)2(NO3)4}-NO3·H2O]n (2), were synthesized by self-assembly of AgNO3 with the designed non-chelating heterocyclic ligand bmpb(bmpb=1,4-bis(4,6-dimethyl-2-pyrimidinyl)methylsulfanyl)-benzene) and the chelating heterocyclic ligand bpsq (bpsq=2,3-bis[(2-pyrimidinyl)methylsulfanyl]-quinoxaline) and characterized by X-ray single-crystal diffraction analyses. For 1, bmpb serves as abidentate ligand and bridges two Ag(I) centers with two nitrogen atoms from different bimethylpyrimidine rings to form a chainstructure. In complex 2, bpsq functions in a hexadentate fashion, in which two sulfur atoms, two nitrogen atoms from quinoxalinering and two nitrogen atoms from different pyrimidine rings bind to four different Ag(I) centers. Sulfur atoms and adjacentnitrogen atoms from quinoxaline ring chelate with Ag(I) to form stable five-membered rings. The nitrate anions, as a template forthe formation of 2-D lamellar structure, act as terminal ligands, bridging ligands and counter ions. © 2001 Published by ElsevierScience Ltd.

Keywords: Zigzag chains; Lamellar structures; Heterocyclic ligands; Silver(I) complexes

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1. Introduction

The design and synthesis of metal-organic coordina-tion polymers from versatile multidentate bridging lig-ands and transitional metal ions have been rapidlyexpanding due to intriguing structural diversity andpotential application as functional materials. Of thesepolymers, the number, type and spatial disposition ofthe binding site of ligands and the stereoelectronicpreferences of metal ions are principally crucial to theconstruction of a specific supramolecular structure ortopology [1–5]. In the preparation of multifunctionalligands, many molecular building blocks with specificstructural information such as thioether–pyridine andthioether–pyrimidine have been employed for buildingup supramolecular architecture [6–10,25]. For example,metal–thiolato complexes are inclined to adopt various

nuclearity and great structural complexity, and silver(I)exhibits a high thiophilicity and labile coordinationmodes with coordination number two to five all occur-ring. Therefore, the self-assembly of coordinatively flex-ible Ag(I) with multidentate ligands, especially thoseligands containing thiolato donor atoms, can producevarious fascinating structural topologies [11–14]. Some-times, besides the nature of ligands and metal ions,other factor such as the counter ions, solvent, reactiontemperature and the ratio of metal to ligand have alsoplayed important roles in the generation of moleculararchitecture [14–22].

In previous studies, our group has concentrated onusing some simple heterocyclic ligands containing nitro-gen and thiolato donor atoms with coordinately flexiblesilver(I) ions for supramolecular synthesis and obtainedsome supramolecular polymers with linear chain or 3-Dnetwork structures [23–26]. Recently, we have designeda serial of versatile bridging ligands by using the simpleligands used in the earlier work, such as non-chelating

* Corresponding author. Fax: +86-591-379-2460.E-mail address: hmc@ms.fjirsm.ac.cn (M.-C. Hong).

0277-5387/01/$ - see front matter © 2001 Published by Elsevier Science Ltd.PII: S 0 2 7 7 -5387 (01 )00929 -9

R.-H. Wang et al. / Polyhedron 20 (2001) 3165–31703166

heterocyclic ligands 2,4,6-tris[(4-pyridyl)methylsul-fanyl]-1,3,5-triazine (tpst), 1,2-bis[(2-pyrimidinyl)-methylsulfanyl]-benzene (bpsb), 1,2-bis[(4-pyridyl)-methylsulfanyl]-benzene (bpb) and chelating hetero-cyclic ligand 2,6-bis[(2-pyrimidinyl)methylsulfanyl]-pyr-idine (bpsp) and obtained some novel structural motifs[23–28]. In order to further investigate the interactionof the ligands containing a thiolato donor atom withcoordinately flexible silver(I) to form coordination

Table 2Selected bond lengths (A� ) and bond angles (°) for 1

Bond lengthsAg(1)�O(1) 2.363(6)Ag(1)�N(1) 2.258(7)

Ag(1)�O(1B) 2.465(7)

Bond anglesN(1)�Ag(1)�O(1B) 138.4(2) 128.8(2)N(1)�Ag(1)�O(1B)O(1)�Ag(1)�O(1B) 85.2(2)

Symmetry transformations used to generate equivalent atoms: B:−x+1, −y+1, −z+1.

Scheme 1.

Table 3Selected bond lengths (A� ) and bond angles (°) for 2

Bond lengthsAg(1)�O(4) 2.319(5) Ag(1)�N(3) 2.364(5)

2.458(8) Ag(1)�S(1)Ag(1)�O(1) 2.763(2)2.215(5)Ag(2)�N(1A) Ag(2)�N(4) 2.296(5)2.589(5) Ag(2)�S(2)Ag(2)�O(5B) 2.878(2)2.225(4)Ag(3)�N(6)

Bond anglesO(4)�Ag(1)�O(1)129.8(2)O(4)�Ag(1)�N(3) 129.8(3)

120.5(2)O(4)�Ag(1)�S(1)93.3(2)N(3)�Ag(1)�O(1)74.9(1)N(3)�Ag(1)�S(1) O(1)�Ag(1)�S(1) 91.4(3)

N(1A)�Ag(2)�N(4) 156.4(2) N(1A)�Ag(2)�O(5B) 121.6(2)79.6(2)N(4)�Ag(2)�O(5B) N(1A)�Ag(2)�S(2) 117.7(1)

N(4)�Ag(2)�S(2) 73.6(1) O(5B)�Ag(2)�S(2) 79.2(1)N(6)�Ag(3)�N(6C) 146.2(3)

Symmetry transformations used to generate equivalent atoms: A:x−1/2, y, −z−1; B: x−1/2, y, −z ; C: −x−1/2, −y+1, z.

Table 1Crystallographic data for the two crystal structures

Compound [Ag2(bmpb)- {[Ag5(bpsq)2(NO3)4]-(NO3)2]n NO3·H2O}n

Empirical formula C36H30Ag5N17O16S4C20H22Ag2N6O6S2

722.30Formula weight 1624.360.32×0.26×0.23 0.42×0.37×0.25Crystal size (mm)

orthorhombictriclinicCrystal systemP1�Space group Pnna4.6494(4)a (A� ) 17.0108(1)10.4474(7)b (A� ) 27.9953(5)12.785(1)c (A� ) 10.2189(2)84.239(3)� (°)86.169(3)� (°)82.596(2)� (°)

V (A� 3) 4866.5(1)611.80(8)1Z 4

2.2171.960Dcalc (g cm−3)1.821� (mm−1) 2.237293(2) 293(2)T (K)0.71073�(Mo K�) (mm) 0.710733182Reflections collected 130022143Unique reflections 4294

3037Observed reflections 996(F�4.0�(F))

Parameters 163 3541.004S on F2 1.0800.0672R1 0.04570.1484Rw 0.0744

��min and ��max 0.573 and −1.478 0.769 and −0.712(e A� −3)

polymers, we have prepared a non-chelating ligand1,4-bis(4,6-dimethyl-2-pyrimidinyl)methylsulfanyl]-ben-zene (bmpb) and a chelating ligand 2,3-bis[(2-pyrim-idinyl)methylsulfanyl]-quinoxaline (bpsq) (Scheme 1),from which two silver(I) coordination polymers,[Ag2(bmpb)(NO3)2]n (1) and [{Ag5(bpsq)2(NO3)4}NO3·H2O]n (2), were obtained.

2. Experimental

2.1. Materials and physical measures

All reagents were commercially available and used aspurchased without further purification. Sodium 4,6-dimethyl-pyrimidine-2-thiolate and sodium pyrimidine-2-thiolate were obtained through the reaction of4,6-dimethyl-2-mercaptopyrimidine and 2-mercaptopy-rimidine with NaOCH3 in MeOH, respectively. The IRspectra as KBr disks were recorded on a Magna 750FT–IR spectrophotometer. Elemental analyses werecarried out by the elemental analysis group in thisinstitute.

R.-H. Wang et al. / Polyhedron 20 (2001) 3165–3170 3167

2.2. Synthesis of metal complexes

2.2.1. [Ag2(bmpb)(NO3)2]n (1)A solution of 1,4-bis(bromomethyl)benzene (0.13 g,

0.5 mmol) and sodium 4,6-dimethyl-pyrimidine-2-thio-late (0.16 g, 1 mmol) in DMF (15 ml) was heated to 50°C for 6 h with vigorous stirring. After cooling, asolution of AgNO3 (0.34 g, 2 mmol) in CH3CN (10 ml)was added. The reaction mixture was stirred for 30 minand then filtered to give a pale yellow solution. Color-less crystalline complex 1 was obtained by diffusion ofdiethyl ether into the resultant solution after 6 days.Yield: 0.21 g (0.29 mmol, 58.33%). Anal. Found: C,33.17; H, 3.11; N, 11.68; S, 8.73. Calc. forC20H22Ag2N6O6S2: C, 33.25; H 3.04; N, 11.63; S,8.88%. IR (KBr pellet): 3032(vw), 2985(vw), 2960(vw),2933(vw), 2426(vw), 1581(s), 1531(m), 1510(w),1433(w), 1385(vs), 1342(w), 1267(s), 1236(m), 1200(w),1174(vw), 1007(vw), 953(vw), 889(w), 862(w), 825(w),766(m), 688(m), 548(w), 526(w) cm−1.

2.2.2. {[Ag5(bpsq)2(NO3)4]NO3 ·H2O}n (2)A solution of 2,3-bis(bromomethyl)quinoxaline (0.16

g, 0.5 mmol) and sodium pyrimidine-2-thiolate (0.15 g,1 mmol) in DMF (20 ml) was heated to 50 °C for 6 hwith vigorous stirring. After cooling, a solution ofAgNO3 (0.43 g, 2.5 mmol) in CH3CN (25 ml) wasadded. The reaction mixture was stirred for 30 min andthen filtered to give a pale yellow solution. Colorlesscrystalline complex 2 was obtained by diffusion ofdiethyl ether into the resultant solution after 3 days.Yield: 0.32 g (0.20 mmol, 75.61%). Anal. Found: C,26.39; H, 1.74; N, 14.72; S, 7.73. Calc. forC36H30Ag5N17O16S4: C, 26.62; H, 1.85; N, 14.65; S,7.89%. IR (KBr pellet): 3134(vw), 3074(vw), 3059(vw),2918(w), 1749(vw), 1630(vs), 1568(vs), 1489(m),1464(w), 1387(vs), 1333(vs), 1286(2), 1205(m), 1178(s),1132(m), 1093(m), 930(w), 854(w), 808(w), 764(m),735(w), 646(m), 565(vw), 472(w), 451(vw) cm−1

.

2.3. X-ray crystallography

Intensity data for 1 and 2 were measured on aSiemens Smart CCD diffractometer with graphite-monochromated Mo K� radiation (�=0.71073 A� ) at298 K. Empirical absorption corrections were appliedby using the SADABS program. The structures weresolved by direct methods and all calculations wereperformed using the SHELXL PC program. The posi-tions of H atoms were generated geometrically (C�Hbond fixed at 0.96 A� ), assigned isotropic thermalparameters and allowed to ride on their parent carbonatoms before the final cycle of refinement. The structurewas refined by full-matrix least-squares minimization of�(Fo−Fc)2 with anisotropic thermal parameters for allatoms except the H atoms. Table 1 gives the crystaldata and structure determination summary for 1 and 2,and Tables 2 and 3 list the selected bond lengths andangles for 1 and 2.

3. Results and discussion

The ligand bmpb was prepared in situ from thereaction of 1,4-bis(bromomethyl)benzene and sodium4,6-dimethyl-pyrimidine-2-thiolate in DMF. The reac-tion of AgNO3 with bmpb ligand was carried out in ametal-to-ligand ratio of 2:1 in DMF/CH3CN. Slowlydiffusing diethyl ether into the resulting solution pro-duced crystals suitable for single crystal X-ray diffrac-tion. The crystallographic analysis of complex 1 revealsthat its structure is an infinite zigzag chain. As shown inFig. 1, each bmpb molecule acts as a bidentate ligand,in which two nitrogen atoms from differentdimethylpyrimidine rings coordinate to two differentmetal atoms in opposite directions. The average dis-tance between the silver(I) and adjacent sulfur atomfrom the bmpb is 3.187 A� , which is considered asinsignificant. Therefore, the Ag(I) adopts a distorted

Fig. 1. View of the zigzag chain in 1.

R.-H. Wang et al. / Polyhedron 20 (2001) 3165–31703168

Fig. 2. (a) View of the basic [Ag5(bpsq)2(NO3)4]NO3·H2O in 2. (b) View of hexasilver nanocavity in 2 with uncoordinated NO3− and H2O were

omitted. (c) Crystal packing with uncoordinated NO3− and H2O omitted along b axis in 2.

trigonal planar coordination and is coordinated by anitrogen atom from dimethylpyrimidine ring and twooxygen atoms from different nitrate anions. The Ag�Nand Ag�O bonds fall in the range of 2.258(7) A� and2.363(6)–2.465(7) A� , respectively. An important featureof the nitrate anions is that they bridge two silver atomswith an oxygen atom to form a Ag2O2 rectangle. Thezigzag chain structure in 1 is very different from thecentrosymmetric dimetalloparacyclophane obtained by

the self-assembly of the analogous ligand bis(2-pyridyl-sulfunylmethyl)benzene with AgNO3 [7].

To further study the influence of the nitrate anion onthe self-assembly of supramolecular complexes, achelating multidentate ligand bpsq was designed. Simi-lar to complex 1, AgNO3 with bpsq in a metal-to-ligandratio of 3:1 gave rise to a 2-D lamellar polymer 2.

The structural feature of 2 is shown in Fig. 2; eachbpsq molecule functions in a hexadentate mode, in

R.-H. Wang et al. / Polyhedron 20 (2001) 3165–3170 3169

Fig. 2. (Continued)

which sulfur atoms and adjacent nitrogen atoms fromquinoxaline ring chelate with silver atoms to form twostable five-membered rings; two nitrogen atoms fromdifferent pyrimidine rings bridge between non-chelatedAg(I) and chelated Ag(I) in opposite directions. Nitratecounter ions adopt two kinds of coordination modeswhich are very different from that of the nitrate anionsin complex 1. One serves as a terminal ligand with anoxygen atom, the other bridges two chelated Ag(I)atoms with two oxygen atoms. Thus, bpsq moleculesand nitrate anions bridge two silver atoms to form a2-D lamellar structure with a centrosymmetric hexasil-ver nanocavity which is very different from the crown-like hexasilver nanocavity [25]. The three independentsilver atoms have different coordination environments.The coordination geometry of Ag(1) is a distortedtetrahedron, in which a sulfur atom and an adjacentnitrogen atom from the quinoxaline ring chelate withAg(1) to form a stable five-membered ring, and twooxygen atoms from a bridging nitrate anion and aterminal nitrate anion bind to Ag(1) with an O�Ag�Obond angle of 129.8(3) to complete the coordinationsphere about Ag(1). The distance of Ag(1)�O(4)brid

(2.319(5) A� ) is shorter than that of Ag(1)�O(1)term

(2.458(8) A� ). Ag(2) adopts a distorted tetrahedral coor-dination, being chelated by a sulfur atom and a nitro-gen atom from the quinoxaline ring similar to Ag(1)and bonded by a nitrogen atom from the pyrimidinering of another bpsq molecule and an oxygen atomfrom another bridging nitrate anion. The bond distanceof Ag(2)�N(4)qui (2.296(5) A� ) is shorter than that ofAg(1)�N(3)qui (2.319(5) A� ), but the bond lengths ofAg(2)�S(2) (2.878(2) A� ) and Ag(2)�O(5a) (2.589(5) A� )are longer than those of Ag(1)�S(1) (2.763(2) A� ) and

Ag(1)�O(4) (2.319(5) A� ), respectively. Ag(3) lies on atwofold axis and is coordinated by two pyrimidyl nitro-gen atoms from different bpsq molecules to form ahighly distorted linear geometry with a Ag�N bonddistance of 2.225(4) A� and N�Ag�N bond angle of146.2(3)°.

4. Conclusions

Self-assembly of silver nitrate with nonchelating lig-and bmpb and chelating ligand bpsq results in a zigzagchain and a 2-D lamellar polymer, respectively, inwhich the ligands bridge two Ag(I) atoms in oppositedirections by two nitrogen atoms from differentdimethylpyrimidine or pyrimidine rings. Nitrate anionswhich serve as the template for the formation of thetwo complexes exhibit two different bridging modes incoordinating to Ag(I) atoms, besides serving as a termi-nal ligand and counter anions in 2. The result of thisstudy illustrates that multidentate ligands, suitablemetal ions and counter ions play an important role inthe construction of metal supramolecular architectures.

5. Supplementary data

Supplementary data have been deposited with theCambridge Crystallographic Centre, CCDC Nos.158440 and 158441. Copies of this information may beobtained free of charge from The Director, CCDC, 12Union Road, Cambridge, CB2 1EZ, UK (fax: +44-1223-336033; email: deposit@ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).

R.-H. Wang et al. / Polyhedron 20 (2001) 3165–31703170

Acknowledgements

The authors are grateful to the National NatureScience Foundation of China and the Key Project ofChinese Academy of Science for financial support.

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