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Three Ag(I)–cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands
Three Ag(I)-cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands Min Shao, Ming-Xing Li, Xue-Qin Wang, Heng-Hua Zhang PII: DOI: Reference:
S1387-7003(15)30011-3 doi: 10.1016/j.inoche.2015.06.030 INOCHE 6035
To appear in:
Inorganic Chemistry Communications
Received date: Revised date: Accepted date:
9 March 2015 26 June 2015 29 June 2015
Please cite this article as: Min Shao, Ming-Xing Li, Xue-Qin Wang, Heng-Hua Zhang, Three Ag(I)-cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands, Inorganic Chemistry Communications (2015), doi: 10.1016/j.inoche.2015.06.030
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Three Ag(I)-cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands
Instrumental Analysis and Research Center, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, P. R. China Department of Chemistry, College of Sciences, Shanghai University, Shanghai 200444, P. R. China
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Min Shao,a,* Ming-Xing Li,b Xue-Qin Wang,b Heng-Hua Zhanga,*
Abstract: Hydrothermal reactions of AgNO3, K3[Fe(CN)6] with N-heterocyclic ligands afforded three
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novel Ag(I)-cyanide coordination polymers, [Ag2(CN)2(tpt)]n (1), {[Ag(CN)(bpe)0.5][Ag(CN)]}n (2) and [Ag(CN)(btmb)0.5]n (3) (tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine, bpe = 1,2-bis(4-pyridyl)ethane, btmb = 1,2-bis(1,2,4-triazol-1-ylmethyl)benzene). In complex 1, two Ag(CN) linear chains are bridged
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by bidentate tpt ligand to form a ladder-like structure, which are further connected by Ag–Ag metal
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bond to generate a 2D polymeric network. Complex 2 is an interesting 3D supramolecular architecture assembled by 2D [Ag1(CN)(bpe)0.5]n network and linear [Ag2(CN)]n chain combined by strong Ag–Ag
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metal bond. Complex 3 is a 1D ladder-like double-chain polymer constructed from Ag-cyanide linear chains and btmb spacer, which is further extended to a 2D supramolecular network by Ag…Ag weak
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interaction. The Ag–Ag metal interactions play important roles in the construction of three coordination polymers. Complexes 1 and 2 are respectively thermally stable to 300 and 180 ºC. Complexes 1 and 3 emit strong blue luminescence. Keywords: Ag(I) complex; Cyanide; N-heterocycle; Crystal structure; Metal bond; Luminescence. * Corresponding authors. Tel: +86-21-66135058. E-mail: [email protected] (M. Shao); [email protected] (H.-H. Zhang) The design, synthesis and crystal engineering of coordination polymers continue to be a quite active research field because of their intriguing structural motifs and potential applications as functional materials [1-3]. The diversity in the coordination structures is attributed to the selection of metal ions and organic ligands as well as synthetic methods. Over the past two decades, transition metal cyanides have been studied extensively due to their great importance in magnetism and luminescence [4,5].
ACCEPTED MANUSCRIPT Copper(I) cyanide system is attractive from the viewpoint of crystal engineering, because the cyanide group, as a small anion with little steric hindrance, is a perfect candidate as linear connector [6-8]. The synthetic strategies of Cu(I)-cyanide coordination polymers are either combining N-heterocycle to 1D
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CuCN chain, or using Cu(II) salt as precursor and K3[Fe(CN)6] as cyanide source which afford Cu(I)-cyanide complexes under hydrothermal condition [9-11]. Analogous to Cu(I) ion, Ag(I) is in
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favor of trigonal or tetrahedral coordination in the presence of cyanide group and N-heterocycle [12], which gives the possibility of promoting the formation of high-dimensional Ag(I)-cyanide polymeric networks. Moreover, Ag(I) complexes display unique argentophilic interaction (Ag–Ag metal bond)
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and arouse attention in recent years [13]. However, in contrast to the rich Cu(I)-cyanide complexes, a few Ag(I)-cyanide complexes have been reported [14-16]. In the course of our investigation for
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Cu(I)-cyanide complexes [17-19], we expand our research to Ag(I)-cyanide complex. Three novel Ag(I)-cyanide coordination polymers were successfully prepared and structurally characterized.
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A mixture of AgNO3 (0.3 mmol), K3[Fe(CN)6] (0.1 mmol), tpt (0.05 mmol) and 8 mL water was
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sealed in a 15 mL Teflon-lined reactor and heated at 160 ºC for 72 h to afford colorless crystals of 1 with 32% yield based on Ag. Anal. calcd for C20H12Ag2N8(%): C, 41.41; H, 2.08; N, 19.31. Found: C,
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41.35; H, 2.15; N, 19.39. IR: 3035w, 2143m, 1573m, 1516vs, 1373s, 1311m, 1061m, 801s, 642s cm–1. Similarly, a mixture of AgNO3 (0.2 mmol), K3[Fe(CN)6] (0.1 mmol), bpe (0.05 mmol) and 8 mL water
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was heated at 140 ºC to afford colorless crystals of 2 with 40% yield. Anal. calcd for C8H6Ag2N3(%): C, 26.70; H, 1.68; N, 11.68. Found: C, 26.66; H, 1.76; N, 11.72. IR: 2928w, 2861w, 2161s, 2120s, 1604s, 1558m, 1419s, 1220m, 1068m, 1014m, 828s, 547s cm–1. A mixture of AgNO3 (0.3 mmol), K3[Fe(CN)6] (0.3 mmol), btmb (0.05 mmol) and 8 mL water was heated at 180 ºC to afford colorless crystals of 3 with 12% yield. Anal. calcd for C7H6AgN4(%): C, 33.09; H, 2.38; N, 22.06. Found: C, 33.14; H, 2.26; N, 22.08. IR: 3134m, 2125s, 1515s, 1429m, 1279s, 1137s, 1013s, 751s, 671s cm–1. Generally, AgCN and KAg(CN)2 were used to prepare Ag-cyanide complexes in literature. Herein we use AgNO3 as silver source and successfully prepare three Ag-cyanide complexes. Obviously, K3[Fe(CN)6] acts as a cyanide source which can slowly release cyanide upon heat treatment [9, 20]. X-ray structural analysis [21] revealed that complex 1 assumes a 2D polymeric network. Ag1 and Ag2 are both in a trigonal geometry, coordinated by two cyanides and a pyridyl group (Fig. 1a). The Ag1–N1, Ag1–C1 and Ag1–N3 bond lengths are 2.098(8), 2.125(5) and 2.512(5) Å, respectively. The
ACCEPTED MANUSCRIPT bond lengths around Ag2 center are slightly different. The Ag2–N2, Ag2–C2 and Ag2–N7 are 2.106(8), 2.119(5) and 2.476(5) Å, respectively. Tpt bidentate ligand combines Ag1 and Ag2 via two pyridyl groups. Three pyridyl groups of tpt are nearly planar with the central triazine ring. Two different
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cyanides play 2-bridges to link Ag1 and Ag2 ions. This results in the formation of two 1D Ag(CN) linear chains. The two Ag(CN) linear chains are parallel arranged and further connected by tpt
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connector to form a ladder-like [Ag2(CN)2(tpt)]n chain (Fig. 1b). The distance between adjacent two parallel tpt ligands is 5.223 Å. These ladder-like chains are parallel arranged. Interestingly, Ag2 is combined to Ag2A in adjacent ladder and forms a Ag–Ag metal bond. The Ag–Ag distance is 3.2675(1)
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Å, which is shorter than the sum of van der Waals radii for silver (3.44 Å). This phenomenon is known as argentophilic interaction [12,13]. The ladder-like building units are connected by Ag–Ag bond to
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form the final 2D polymeric network of 1 (Fig. 1b).
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[Figure 1 here]
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Complex 2 is a 3D supramolecular framework assembled by 2D [Ag1(CN)(bpe)0.5]n network and [Ag2(CN)]n linear chain. Two distinct Ag(I) ions show trigonal and linear coordination geometries (Fig.
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2a). Ag1 is three-coordinated by two 2-cyanides and a pyridyl group, which is deviated a little from the trigonal plane with approximate 0.067 Å. The Ag1–N1, Ag1–N3 and Ag1–C1 bond lengths are 2.144(10), 2.252(6) and 2.259(7) Å, respectively. Ag2 is linearly two-coordinated by two 2-cyanides
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with a N2–Ag2–C2 bond angle of 165.9(3)°. The Ag2–N2 and Ag2–C2 bond lengths are 2.051(7) and 2.052(7) Å, respectively. Ag1 is linked by 2-cyanide to form a wave-like [Ag1(CN)]n chain. These [Ag1(CN)]n chains are parallel arranged and further connected by bidentate bpe spacer to construct a 2D sheet-like [Ag1(CN)(bpe)0.5]n network (Fig. 2b). Ag2 is linearly linked by 2-cyanide to form a 1D [Ag2(CN)]n infinite chain. Interestingly, Ag1 combines to Ag2 via metal bond. The Ag1–Ag2 bond length is 3.056(1) Å, which is obviously stronger than the Ag–Ag bond in complex 1. In aid of the Ag–Ag bond, the wave-like [Ag1(CN)]n chain and the linear [Ag2(CN)]n chain are combined together to form a 3D supramolecular Ag-cyanide framework (Fig. 2c). The bpe bidentate ligand is incorporated into the 3D framework to complete the final 3D supramolecular architecture of 2 (Fig. 2d). [Figure 2 here] Complex 3 is a 1D ladder-like double chain polymer. Ag1 adopts a trigonal geometry, coordinated
ACCEPTED MANUSCRIPT by two 2-cyanides and a pyridyl group (Fig. 3a). The Ag1–N1, Ag1–N2 and Ag1–C1 bond lengths are 2.118(5), 2.348(3) and 2.195(4) Å, respectively. Cyanide acts as a bidentate bridge and links Ag(I) ions to form a 1D Ag-cyanide chain. Btmb is a bidentate ligand and connects to two Ag(I) ions via two
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triazole terminals. Two 1D Ag-cyanide chains are parallel arranged and further connected by btmb spaces to construct a 1D ladder-like double chain (Fig. 3b). The vertical inter-plane distance between
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two adjacent btmb is 5.152(1) Å. Furthermore, such ladder-like double chains are parallel arranged and extended to a 2D supramolecular network by Ag…Ag weak interaction (Fig. S1). The nearest Ag…Ag
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distance is 3.57 Å, obviously longer than the Ag–Ag metal bond in 1 and 2. [Figure 3 here]
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Thermal analyses of 1 and 2 were performed in 30-800 °C, except complex 3 due to poor yield. Complex 1 was stable up to 300 °C without weight-loss (Fig. S2). In 300-360 ºC, it rapidly
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decomposed to release tpt and produced 49.14% AgCN intermediate (calcd 53.83%). AgCN
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decomposed slowly and left 38.31% Ag2O residue at 800 °C (calcd 39.95%). Complex 2 was stable to 180 ºC, and then rapidly decomposed in 180-230 ºC. This weight-loss procedure corresponds to release
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bpe and afforded 78.02% AgCN intermediate (calcd 74.41%). AgCN decomposed continuously to 800 °C. A final residue was Ag2O (found 65.34%, calcd 64.39%). The luminescence of 1-3 were investigated in the solid state (Fig. S3). Upon excitation at 391 nm,
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complex 1 exhibits a strong blue luminescent band with an emission peak at 457 nm, which can be assigned as metal-to-ligand charge transfer (MLCT) mechanism [12, 23]. Complex 2 shows a weak emission peak at 468 nm under the excitation of 391 nm light. This weak emission maybe originates from the flexible ethyl group of bpe ligand, in contrast with the rigid tpt in 1. Complex 3 exhibits a strong blue luminescent band with an emission peak at 468 nm under the excitation of 434 nm light, which is assigned to ligand-centered emission. In conclusion, three Ag(I)-cyanide coordination polymers have been constructed by tuning different N-heterocyclic ligands. Complex 2 is an interesting 3D supramolecular architecture assembled by 2D [Ag1(CN)(bpe)0.5]n sheet-like network and [Ag2(CN)]n linear chain combined by strong Ag–Ag metal bond. Complexes 1 and 3 both contain ladder-like double chains. The Ag–Ag metal interactions play important roles in the construction of three coordination polymers. Complexes 1 and 2 are respectively
ACCEPTED MANUSCRIPT thermally stable to 300 and 180 ºC. Complexes 1 and 3 emit strong blue luminescence. Acknowledgment. Financially supported by the National Natural Science Foundation of China
References
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[1] H.C. Zhou, J.R. Long, O.M. Yaghi, Chem. Rev. 112 (2012) 673.
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(21171115).
[2] T.R. Cook, Y.R. Zheng, P.J. Stang, Chem. Rev. 113 (2013) 734.
[3] Z.J. Lin, J. Lü, M.C. Hong, R. Cao, Chem. Soc. Rev. 43 (2014) 5867.
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[4] S. Wang, X.H. Ding, J.L. Zuo, X.Z. You, W. Huang, Coord. Chem. Rev. 255 (2011) 1713.
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[5] E. Colacio, R. Kivekas, F. Lloret, M. Sunberg, J. Suarez-Varela, M. Bardaji, A. Laguna, Inorg. Chem. 41 (2002) 5141. [6] R.D. Pike, Organometallics 31 (2012) 7647.
, E. Marelli, A.C. Hannon, C. Allain, R. Pansu, F. Hartl, J. Am.
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[7] A.M. Chippindale, S.J. Hibble, E.J. Chem. Soc. 134 (2012) 16387.
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[8] J.P. Lang, Q.F. Xu, Z.N. Chen, B.F. Abrahams, J. Am. Chem. Soc. 125 (2003) 12682.
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[9] M.J. Lim, C.A. Murray, T.A. Tronic, K.E. deKrafft, A.N. Ley, J.C. deButts, R.D. Pike, H. Lu, H.H. Patterson, Inorg. Chem. 47 (2008) 6931. [10] Y.L. Qin, J.J. Hou, J. Lv, X.M. Zhang, Cryst. Growth Des. 11 (2011) 3101. [11] J. Xia, Z.J. Zhang, W. Shi, J.F. Wei, P. Cheng, Cryst. Growth Des. 10 (2010) 2323.
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[12] X. Liu, G.C. Guo, M.L. Fu, X.H. Liu, M.S. Wang, J.S. Huang, Inorg. Chem. 45 (2006) 3679. [13] H. Schmidbaur, A. Schier, Angew. Chem. Int. Ed. 54 (2015) 746. [14] V. Urban, T. Pretsch, H. Hartl, Angew. Chem., Int. Ed. 44 (2005) 2794. [15] G.C. Guo, Q.M. Wang, T.C.W. Mak, Inorg. Chem. Commun. 3 (2000) 313. [16] J.Y. Li, Z.P. Ni, Z. Yan, Z.M. Zhang, Y.C. Chen, W. Liu, M.L. Tong, CrystEngComm 16 (2014) 6444. [17] H. Wang, M.X. Li, M. Shao, X. He, Polyhedron 26 (2007) 5171. [18] S.W. Liang, M.X. Li, M. Shao, Z.X. Miao, Inorg. Chem. Commun. 9 (2006) 1312. [19] M.X. Li, Z.X. Miao, M. Shao, S.W. Liang, S.R. Zhu, Inorg. Chem. 47 (2008) 4481. [20] H. Mao, C. Zhang, C. Xu, H. Zhang, X. Shen, B. Wu, Y. Zhu, Q. Wu, H. Wang, Inorg. Chim. Acta 358 (2005) 1934. [21] Crystal data of 1: C20H12Ag2N8, Mr = 580.12, triclinic, space group P-1, a = 5.223(1), b = 8.064(2), c = 24.515(5) Å, = 96.418(3), = 93.293(2), = 104.748(2)º, V = 988.2(4) Å3, Z = 2, Dc = 1.950 g cm−3,
ACCEPTED MANUSCRIPT R1 = 0.0512, wR2 = 0.1400 for 3436 unique reflections and 272 parameters, S = 1.099. Crystal data of 2: C8H6Ag2N3, Mr = 359.90, monoclinic, space group P21/n, a = 10.174(2), b = 9.159(2), c = 10.433(2) Å, Dc = 2.459 g cm−3, R1 = 0.0446, wR2 = 0.0876 for 1706 unique reflections and 118 parameters, S = 1.099. Crystal data of 3: C7H6AgN4, Mr = 254.03,
= 90.750(2)º, V = 972.1(3) Å3, Z = 4,
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monoclinic, space group P21/c, a = 12.454(1), b = 5.1522(5), c = 13.149(1) Å, = 109.179(1)º, V = 796.86(13) Å3, Z = 4, Dc = 2.117 g cm−3, R1 = 0.0295, wR2 = 0.0673 for 1406 unique reflections and 110 parameters, S = 1.087. Data were collected on a Bruker Smart Apex-II CCD diffractometer. The structures were solved by direct method and refined by SHELXTL program [22]. [22] G.M. Sheldrick, SHELXTL. Version 6.1, Bruker AXS Inc., Madison, Wisconsin, USA, 2000.
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[23] X. Liu, L. Li, Y.Z. Yang, K.L. Huang, Dalton Trans. 43 (2014) 4086.
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Fig. 1 (a) The coordination structure of 1. (b) The 2D polymeric network of 1 constructing from
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ladder-like [Ag2(CN)2(tpt)]n units combined by Ag–Ag metal bond.
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Fig. 2 (a) The coordination structure of 2. (b) 2D sheet-like [Ag1(CN)(bpe)0.5]n network. (c) 3D
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Ag-cyanide framework constructing from wave-like [Ag1(CN)]n and linear [Ag2(CN)]n chains via
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Ag–Ag bond. (d) 3D supramolecular architecture of 2.
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Fig. 3 (a) The coordination structure of 3. (b) The 1D ladder-like double chain of 3.
ACCEPTED MANUSCRIPT Graphical Abstract—Synopsis
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Min Shao,* Ming-Xing Li, Xue-Qin Wang, Heng-Hua Zhang*
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Three Ag(I)-cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands
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Three Ag(I)-cyanide coordination polymers were constructed based on different N-heterocyclic ligands. Complex 2 is an interesting 3D supramolecular architecture assembled by 2D [Ag1(CN)(bpe)0.5]n
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network and linear [Ag2(CN)]n chain combined by strong Ag–Ag metal bond. Complex 1 and 3 emit
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strong blue luminescence.
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Complex 1 is a 2D network constructing from ladder-like chains combined by Ag–Ag metal bond.
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Complex 2 is a 3D supramolecule assembled by 2D [Ag1(CN)(bpe)0.5]n network and 1D [Ag2(CN)]n chain.
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Complex 3 is a 1D ladder-like double chain polymer.
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Complex 1 and 3 emit strong blue luminescence.
S1387-7003(15)30011-3 doi: 10.1016/j.inoche.2015.06.030 INOCHE 6035
To appear in:
Inorganic Chemistry Communications
Received date: Revised date: Accepted date:
9 March 2015 26 June 2015 29 June 2015
Please cite this article as: Min Shao, Ming-Xing Li, Xue-Qin Wang, Heng-Hua Zhang, Three Ag(I)-cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands, Inorganic Chemistry Communications (2015), doi: 10.1016/j.inoche.2015.06.030
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Three Ag(I)-cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands
Instrumental Analysis and Research Center, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, P. R. China Department of Chemistry, College of Sciences, Shanghai University, Shanghai 200444, P. R. China
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Min Shao,a,* Ming-Xing Li,b Xue-Qin Wang,b Heng-Hua Zhanga,*
Abstract: Hydrothermal reactions of AgNO3, K3[Fe(CN)6] with N-heterocyclic ligands afforded three
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novel Ag(I)-cyanide coordination polymers, [Ag2(CN)2(tpt)]n (1), {[Ag(CN)(bpe)0.5][Ag(CN)]}n (2) and [Ag(CN)(btmb)0.5]n (3) (tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine, bpe = 1,2-bis(4-pyridyl)ethane, btmb = 1,2-bis(1,2,4-triazol-1-ylmethyl)benzene). In complex 1, two Ag(CN) linear chains are bridged
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by bidentate tpt ligand to form a ladder-like structure, which are further connected by Ag–Ag metal
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bond to generate a 2D polymeric network. Complex 2 is an interesting 3D supramolecular architecture assembled by 2D [Ag1(CN)(bpe)0.5]n network and linear [Ag2(CN)]n chain combined by strong Ag–Ag
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metal bond. Complex 3 is a 1D ladder-like double-chain polymer constructed from Ag-cyanide linear chains and btmb spacer, which is further extended to a 2D supramolecular network by Ag…Ag weak
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interaction. The Ag–Ag metal interactions play important roles in the construction of three coordination polymers. Complexes 1 and 2 are respectively thermally stable to 300 and 180 ºC. Complexes 1 and 3 emit strong blue luminescence. Keywords: Ag(I) complex; Cyanide; N-heterocycle; Crystal structure; Metal bond; Luminescence. * Corresponding authors. Tel: +86-21-66135058. E-mail: [email protected] (M. Shao); [email protected] (H.-H. Zhang) The design, synthesis and crystal engineering of coordination polymers continue to be a quite active research field because of their intriguing structural motifs and potential applications as functional materials [1-3]. The diversity in the coordination structures is attributed to the selection of metal ions and organic ligands as well as synthetic methods. Over the past two decades, transition metal cyanides have been studied extensively due to their great importance in magnetism and luminescence [4,5].
ACCEPTED MANUSCRIPT Copper(I) cyanide system is attractive from the viewpoint of crystal engineering, because the cyanide group, as a small anion with little steric hindrance, is a perfect candidate as linear connector [6-8]. The synthetic strategies of Cu(I)-cyanide coordination polymers are either combining N-heterocycle to 1D
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CuCN chain, or using Cu(II) salt as precursor and K3[Fe(CN)6] as cyanide source which afford Cu(I)-cyanide complexes under hydrothermal condition [9-11]. Analogous to Cu(I) ion, Ag(I) is in
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favor of trigonal or tetrahedral coordination in the presence of cyanide group and N-heterocycle [12], which gives the possibility of promoting the formation of high-dimensional Ag(I)-cyanide polymeric networks. Moreover, Ag(I) complexes display unique argentophilic interaction (Ag–Ag metal bond)
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and arouse attention in recent years [13]. However, in contrast to the rich Cu(I)-cyanide complexes, a few Ag(I)-cyanide complexes have been reported [14-16]. In the course of our investigation for
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Cu(I)-cyanide complexes [17-19], we expand our research to Ag(I)-cyanide complex. Three novel Ag(I)-cyanide coordination polymers were successfully prepared and structurally characterized.
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A mixture of AgNO3 (0.3 mmol), K3[Fe(CN)6] (0.1 mmol), tpt (0.05 mmol) and 8 mL water was
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sealed in a 15 mL Teflon-lined reactor and heated at 160 ºC for 72 h to afford colorless crystals of 1 with 32% yield based on Ag. Anal. calcd for C20H12Ag2N8(%): C, 41.41; H, 2.08; N, 19.31. Found: C,
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41.35; H, 2.15; N, 19.39. IR: 3035w, 2143m, 1573m, 1516vs, 1373s, 1311m, 1061m, 801s, 642s cm–1. Similarly, a mixture of AgNO3 (0.2 mmol), K3[Fe(CN)6] (0.1 mmol), bpe (0.05 mmol) and 8 mL water
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was heated at 140 ºC to afford colorless crystals of 2 with 40% yield. Anal. calcd for C8H6Ag2N3(%): C, 26.70; H, 1.68; N, 11.68. Found: C, 26.66; H, 1.76; N, 11.72. IR: 2928w, 2861w, 2161s, 2120s, 1604s, 1558m, 1419s, 1220m, 1068m, 1014m, 828s, 547s cm–1. A mixture of AgNO3 (0.3 mmol), K3[Fe(CN)6] (0.3 mmol), btmb (0.05 mmol) and 8 mL water was heated at 180 ºC to afford colorless crystals of 3 with 12% yield. Anal. calcd for C7H6AgN4(%): C, 33.09; H, 2.38; N, 22.06. Found: C, 33.14; H, 2.26; N, 22.08. IR: 3134m, 2125s, 1515s, 1429m, 1279s, 1137s, 1013s, 751s, 671s cm–1. Generally, AgCN and KAg(CN)2 were used to prepare Ag-cyanide complexes in literature. Herein we use AgNO3 as silver source and successfully prepare three Ag-cyanide complexes. Obviously, K3[Fe(CN)6] acts as a cyanide source which can slowly release cyanide upon heat treatment [9, 20]. X-ray structural analysis [21] revealed that complex 1 assumes a 2D polymeric network. Ag1 and Ag2 are both in a trigonal geometry, coordinated by two cyanides and a pyridyl group (Fig. 1a). The Ag1–N1, Ag1–C1 and Ag1–N3 bond lengths are 2.098(8), 2.125(5) and 2.512(5) Å, respectively. The
ACCEPTED MANUSCRIPT bond lengths around Ag2 center are slightly different. The Ag2–N2, Ag2–C2 and Ag2–N7 are 2.106(8), 2.119(5) and 2.476(5) Å, respectively. Tpt bidentate ligand combines Ag1 and Ag2 via two pyridyl groups. Three pyridyl groups of tpt are nearly planar with the central triazine ring. Two different
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cyanides play 2-bridges to link Ag1 and Ag2 ions. This results in the formation of two 1D Ag(CN) linear chains. The two Ag(CN) linear chains are parallel arranged and further connected by tpt
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connector to form a ladder-like [Ag2(CN)2(tpt)]n chain (Fig. 1b). The distance between adjacent two parallel tpt ligands is 5.223 Å. These ladder-like chains are parallel arranged. Interestingly, Ag2 is combined to Ag2A in adjacent ladder and forms a Ag–Ag metal bond. The Ag–Ag distance is 3.2675(1)
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Å, which is shorter than the sum of van der Waals radii for silver (3.44 Å). This phenomenon is known as argentophilic interaction [12,13]. The ladder-like building units are connected by Ag–Ag bond to
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form the final 2D polymeric network of 1 (Fig. 1b).
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[Figure 1 here]
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Complex 2 is a 3D supramolecular framework assembled by 2D [Ag1(CN)(bpe)0.5]n network and [Ag2(CN)]n linear chain. Two distinct Ag(I) ions show trigonal and linear coordination geometries (Fig.
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2a). Ag1 is three-coordinated by two 2-cyanides and a pyridyl group, which is deviated a little from the trigonal plane with approximate 0.067 Å. The Ag1–N1, Ag1–N3 and Ag1–C1 bond lengths are 2.144(10), 2.252(6) and 2.259(7) Å, respectively. Ag2 is linearly two-coordinated by two 2-cyanides
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with a N2–Ag2–C2 bond angle of 165.9(3)°. The Ag2–N2 and Ag2–C2 bond lengths are 2.051(7) and 2.052(7) Å, respectively. Ag1 is linked by 2-cyanide to form a wave-like [Ag1(CN)]n chain. These [Ag1(CN)]n chains are parallel arranged and further connected by bidentate bpe spacer to construct a 2D sheet-like [Ag1(CN)(bpe)0.5]n network (Fig. 2b). Ag2 is linearly linked by 2-cyanide to form a 1D [Ag2(CN)]n infinite chain. Interestingly, Ag1 combines to Ag2 via metal bond. The Ag1–Ag2 bond length is 3.056(1) Å, which is obviously stronger than the Ag–Ag bond in complex 1. In aid of the Ag–Ag bond, the wave-like [Ag1(CN)]n chain and the linear [Ag2(CN)]n chain are combined together to form a 3D supramolecular Ag-cyanide framework (Fig. 2c). The bpe bidentate ligand is incorporated into the 3D framework to complete the final 3D supramolecular architecture of 2 (Fig. 2d). [Figure 2 here] Complex 3 is a 1D ladder-like double chain polymer. Ag1 adopts a trigonal geometry, coordinated
ACCEPTED MANUSCRIPT by two 2-cyanides and a pyridyl group (Fig. 3a). The Ag1–N1, Ag1–N2 and Ag1–C1 bond lengths are 2.118(5), 2.348(3) and 2.195(4) Å, respectively. Cyanide acts as a bidentate bridge and links Ag(I) ions to form a 1D Ag-cyanide chain. Btmb is a bidentate ligand and connects to two Ag(I) ions via two
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triazole terminals. Two 1D Ag-cyanide chains are parallel arranged and further connected by btmb spaces to construct a 1D ladder-like double chain (Fig. 3b). The vertical inter-plane distance between
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two adjacent btmb is 5.152(1) Å. Furthermore, such ladder-like double chains are parallel arranged and extended to a 2D supramolecular network by Ag…Ag weak interaction (Fig. S1). The nearest Ag…Ag
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distance is 3.57 Å, obviously longer than the Ag–Ag metal bond in 1 and 2. [Figure 3 here]
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Thermal analyses of 1 and 2 were performed in 30-800 °C, except complex 3 due to poor yield. Complex 1 was stable up to 300 °C without weight-loss (Fig. S2). In 300-360 ºC, it rapidly
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decomposed to release tpt and produced 49.14% AgCN intermediate (calcd 53.83%). AgCN
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decomposed slowly and left 38.31% Ag2O residue at 800 °C (calcd 39.95%). Complex 2 was stable to 180 ºC, and then rapidly decomposed in 180-230 ºC. This weight-loss procedure corresponds to release
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bpe and afforded 78.02% AgCN intermediate (calcd 74.41%). AgCN decomposed continuously to 800 °C. A final residue was Ag2O (found 65.34%, calcd 64.39%). The luminescence of 1-3 were investigated in the solid state (Fig. S3). Upon excitation at 391 nm,
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complex 1 exhibits a strong blue luminescent band with an emission peak at 457 nm, which can be assigned as metal-to-ligand charge transfer (MLCT) mechanism [12, 23]. Complex 2 shows a weak emission peak at 468 nm under the excitation of 391 nm light. This weak emission maybe originates from the flexible ethyl group of bpe ligand, in contrast with the rigid tpt in 1. Complex 3 exhibits a strong blue luminescent band with an emission peak at 468 nm under the excitation of 434 nm light, which is assigned to ligand-centered emission. In conclusion, three Ag(I)-cyanide coordination polymers have been constructed by tuning different N-heterocyclic ligands. Complex 2 is an interesting 3D supramolecular architecture assembled by 2D [Ag1(CN)(bpe)0.5]n sheet-like network and [Ag2(CN)]n linear chain combined by strong Ag–Ag metal bond. Complexes 1 and 3 both contain ladder-like double chains. The Ag–Ag metal interactions play important roles in the construction of three coordination polymers. Complexes 1 and 2 are respectively
ACCEPTED MANUSCRIPT thermally stable to 300 and 180 ºC. Complexes 1 and 3 emit strong blue luminescence. Acknowledgment. Financially supported by the National Natural Science Foundation of China
References
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[1] H.C. Zhou, J.R. Long, O.M. Yaghi, Chem. Rev. 112 (2012) 673.
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(21171115).
[2] T.R. Cook, Y.R. Zheng, P.J. Stang, Chem. Rev. 113 (2013) 734.
[3] Z.J. Lin, J. Lü, M.C. Hong, R. Cao, Chem. Soc. Rev. 43 (2014) 5867.
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[4] S. Wang, X.H. Ding, J.L. Zuo, X.Z. You, W. Huang, Coord. Chem. Rev. 255 (2011) 1713.
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[5] E. Colacio, R. Kivekas, F. Lloret, M. Sunberg, J. Suarez-Varela, M. Bardaji, A. Laguna, Inorg. Chem. 41 (2002) 5141. [6] R.D. Pike, Organometallics 31 (2012) 7647.
, E. Marelli, A.C. Hannon, C. Allain, R. Pansu, F. Hartl, J. Am.
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[7] A.M. Chippindale, S.J. Hibble, E.J. Chem. Soc. 134 (2012) 16387.
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[8] J.P. Lang, Q.F. Xu, Z.N. Chen, B.F. Abrahams, J. Am. Chem. Soc. 125 (2003) 12682.
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[9] M.J. Lim, C.A. Murray, T.A. Tronic, K.E. deKrafft, A.N. Ley, J.C. deButts, R.D. Pike, H. Lu, H.H. Patterson, Inorg. Chem. 47 (2008) 6931. [10] Y.L. Qin, J.J. Hou, J. Lv, X.M. Zhang, Cryst. Growth Des. 11 (2011) 3101. [11] J. Xia, Z.J. Zhang, W. Shi, J.F. Wei, P. Cheng, Cryst. Growth Des. 10 (2010) 2323.
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[12] X. Liu, G.C. Guo, M.L. Fu, X.H. Liu, M.S. Wang, J.S. Huang, Inorg. Chem. 45 (2006) 3679. [13] H. Schmidbaur, A. Schier, Angew. Chem. Int. Ed. 54 (2015) 746. [14] V. Urban, T. Pretsch, H. Hartl, Angew. Chem., Int. Ed. 44 (2005) 2794. [15] G.C. Guo, Q.M. Wang, T.C.W. Mak, Inorg. Chem. Commun. 3 (2000) 313. [16] J.Y. Li, Z.P. Ni, Z. Yan, Z.M. Zhang, Y.C. Chen, W. Liu, M.L. Tong, CrystEngComm 16 (2014) 6444. [17] H. Wang, M.X. Li, M. Shao, X. He, Polyhedron 26 (2007) 5171. [18] S.W. Liang, M.X. Li, M. Shao, Z.X. Miao, Inorg. Chem. Commun. 9 (2006) 1312. [19] M.X. Li, Z.X. Miao, M. Shao, S.W. Liang, S.R. Zhu, Inorg. Chem. 47 (2008) 4481. [20] H. Mao, C. Zhang, C. Xu, H. Zhang, X. Shen, B. Wu, Y. Zhu, Q. Wu, H. Wang, Inorg. Chim. Acta 358 (2005) 1934. [21] Crystal data of 1: C20H12Ag2N8, Mr = 580.12, triclinic, space group P-1, a = 5.223(1), b = 8.064(2), c = 24.515(5) Å, = 96.418(3), = 93.293(2), = 104.748(2)º, V = 988.2(4) Å3, Z = 2, Dc = 1.950 g cm−3,
ACCEPTED MANUSCRIPT R1 = 0.0512, wR2 = 0.1400 for 3436 unique reflections and 272 parameters, S = 1.099. Crystal data of 2: C8H6Ag2N3, Mr = 359.90, monoclinic, space group P21/n, a = 10.174(2), b = 9.159(2), c = 10.433(2) Å, Dc = 2.459 g cm−3, R1 = 0.0446, wR2 = 0.0876 for 1706 unique reflections and 118 parameters, S = 1.099. Crystal data of 3: C7H6AgN4, Mr = 254.03,
= 90.750(2)º, V = 972.1(3) Å3, Z = 4,
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monoclinic, space group P21/c, a = 12.454(1), b = 5.1522(5), c = 13.149(1) Å, = 109.179(1)º, V = 796.86(13) Å3, Z = 4, Dc = 2.117 g cm−3, R1 = 0.0295, wR2 = 0.0673 for 1406 unique reflections and 110 parameters, S = 1.087. Data were collected on a Bruker Smart Apex-II CCD diffractometer. The structures were solved by direct method and refined by SHELXTL program [22]. [22] G.M. Sheldrick, SHELXTL. Version 6.1, Bruker AXS Inc., Madison, Wisconsin, USA, 2000.
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[23] X. Liu, L. Li, Y.Z. Yang, K.L. Huang, Dalton Trans. 43 (2014) 4086.
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Fig. 1 (a) The coordination structure of 1. (b) The 2D polymeric network of 1 constructing from
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ladder-like [Ag2(CN)2(tpt)]n units combined by Ag–Ag metal bond.
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Fig. 2 (a) The coordination structure of 2. (b) 2D sheet-like [Ag1(CN)(bpe)0.5]n network. (c) 3D
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Ag-cyanide framework constructing from wave-like [Ag1(CN)]n and linear [Ag2(CN)]n chains via
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Ag–Ag bond. (d) 3D supramolecular architecture of 2.
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Fig. 3 (a) The coordination structure of 3. (b) The 1D ladder-like double chain of 3.
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Min Shao,* Ming-Xing Li, Xue-Qin Wang, Heng-Hua Zhang*
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Three Ag(I)-cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands
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Three Ag(I)-cyanide coordination polymers were constructed based on different N-heterocyclic ligands. Complex 2 is an interesting 3D supramolecular architecture assembled by 2D [Ag1(CN)(bpe)0.5]n
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network and linear [Ag2(CN)]n chain combined by strong Ag–Ag metal bond. Complex 1 and 3 emit
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strong blue luminescence.
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Complex 1 is a 2D network constructing from ladder-like chains combined by Ag–Ag metal bond.
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Complex 2 is a 3D supramolecule assembled by 2D [Ag1(CN)(bpe)0.5]n network and 1D [Ag2(CN)]n chain.
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Complex 3 is a 1D ladder-like double chain polymer.
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Complex 1 and 3 emit strong blue luminescence.