Journal of Structural Chemistry. Vol. 52, No. 1, pp. 160-165, 2011 Original Russian Text Copyright © 2011 by H. Ur Rehman, S. Ahmad, H. Ajaz, M. Hanif, M. Altaf, and H. Stoeckli-Evans
CRYSTAL STRUCTURE OF A SILVER(I) COMPLEX {[Ag(N-METHYLTHIOUREA)2]NO3}n EXHIBITING INFINITE CHAINS OF AgS4 TETRAHEDRA 1 2 2 2 © H. Ur Rehman, S. Ahmad, H. Ajaz, M. Hanif, 3 3 M. Altaf, and H. Stoeckli-Evans
UDC 548.736
A polymeric silver(I) complex, bis(N-methylthiourea)silver(I) nitrate, {[Ag(Metu)2]NO3}n is prepared and its crystal structure is determined. The compound crystallizes in the monoclinic C2/c space group. In the structure, distorted AgS4 tetrahedra are linked through the sulfur atoms of the Metu ligand to form isolated infinite chains of the type [Ag(SR)2] nn + . The cationic chains are separated from each other by nitrate ions that do not coordinate to the metal ion. The chains are bridged via N–H…O hydrogen bonds involving the nitrate ions. The complex exhibits an Ag---Ag separation of ∼3.21 Å indicating the existence of significant argentophilic interactions. An upfield shift in the >C=S resonance of Metu in 13C NMR and downfield shift in the N–H resonance in 1H NMR are consistent with sulfur coordination to silver(I). Keywords: Silver(I) complexes, N-methylthiourea, crystal structure.
INTRODUCTION The study of the coordination behavior of thiones is of considerable interest due to their variable binding modes and the relevance of their binding sites to those in living systems [1-18]. Moreover, thiourea complexes are starting materials in chemical spray pyrolysis processes used to produce sulfide thin films [19]. Structural studies on silver(I) complexes of thiourea and its derivatives have shown that silver(I) is quite variable in the geometries of its sulfur coordination, which can vary between linear, trigonal planar and tetrahedral [4, 8-13]. These studies demonstrate that thiones can act both as terminal [8-10] or bridging [4, 11, 12] ligands to form polymeric structures, such as [Ag2(Tmtu)(CN)2]n (Tmetu = tetramethylthiourea) [4]. The versatility in bonding modes is attributed to a large size of the sulfur atom, which makes it easier to adopt different angles at this atom in complexes [20, 21]. The importance of these compounds also motivated us to investigate their structural properties and consequently, we reported the crystal structures of several such complexes [2–5]. Here, we report the crystal structure of bis(N-methylthiourea)silver(I) nitrate [Ag{SC(NH2)(HN(CH3)}2]NO3 (1) that crystallizes in the form of a linear polymeric chain.
EXPERIMENTAL Materials. Silver nitrate was obtained from Panreac Chemical Company, Spain and N-Methylthiourea (Metu) was purchased from Acros Organics, Belgium. 1
Exxelis Limited, ETTC/Biospace, Mayfield Road, Edinburgh EH9 3JF, UK. 2Department of Chemistry, University of Engineering and Technology, Lahore 54890, Pakistan;
[email protected]. 3Institute of Physics, University of Neuchâtel, CH-2009 Neuchâtel, Switzerland. The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 52, No. 1, pp. 164-169, January-February, 2011. Original article submitted July, 25 2009. 160
0022-4766/11/5201-0160
TABLE 1. Summary of Crystal Data and Details of Structure Determination Crystal data Formula Formula weight Crystal system Space group a, b, c, Å α, β, γ, deg V, Å3 Z ρcalc, g/cm3 μ(MoKα), mm–1 F(000) Crystal size, mm
C4H12AgN5O3S2 350.18 Monoclinic C2/c 19.2430(16), 6.4315(4), 18.4142(15) 90, 90.884(7), 90 2278.7(3) 8 2.041 2.132 1392 0.50×0.24×0.22 Data collection
Temperature, K λMoKα, Å θMin–Max, deg h, k, l limits Reflns: Total, Uniq. Data, Rint Observed data [I > 2σ(I)] Absorption: Tmin/Tmax
173 0.71073 2.12-29.25 –26:26, –8:8, –25:25 21253, 3083, 0.0289 2720 0.4325/0.6696 Refinement
Nref, Npar R, wR2, S w = [σ2( F 02 ) + (0.0242P)2 + 1.6454P]–1,
3083, 138 0.0194, 0.0463, 1.053
where P = ( F 02 + 2 F c2 )/3 Max. and Av. Shift/Error Min. and Max. Resd. Dens., e/Å3
C=S (176.0 ppm, 180.0 ppm) and N–CH3 (30.7 ppm, 32.1 ppm) carbons showing that Metu exists in two different forms. However, the downfield signals are of less intensity. For free Metu these resonances appear at 181.0 ppm & 184.0 ppm and 29.8 ppm & 31.0 ppm respectively. X-Ray Structure Description. The molecular structure of 1, along with the crystallographic numbering scheme, is shown in Fig. 1. Selected bond distances and bond angles are given in Table 2. The structure is ionic and consists of [Ag(Metu)2]+ cationic units and nitrate counter ions. The cationic units are linked through sulfur atoms of bridging Metu ligands to form a linear chain of the type [Ag(SR)2] nn + running parallel to the c axis, as shown in Fig. 2. These chains are separated from each other by nitrate anions that do not coordinate to the metal atoms. The silver atom is tetrahedrally coordinated to four sulfur atoms from Metu molecules with S---Ag---S angles varying from 102.901(18)° to 113.918(19)°. The values are indicative of some distortion of the AgS4 tetrahedra. The compound is isostructural to copper(I) complex bis(N,N′-dimethylthiourea)copper(I) nitrate {[Cu(Dmtu)2]NO3}n [30]. In a previously reported silver(I) complex with three Metu molecules chlorotris(methylthiourea)silver(I) [9], the Metu ligand behaves as a terminal ligand, and the structure consists of independent distorted tetrahedral Ag(I) moieties with only weak hydrogen bonds and/or van der Waals interactions between molecules. On the other hand, in the title complex,
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TABLE 2. Selected Bond Distances (Å) and Bond Angles (deg) Bond distances Ag(1)–S(1) Ag(1)–S(2) Ag(1)–Ag(2)#2 Ag(1)–Ag(2) Ag(2)–S(2)#2 Ag(2)–S(1) N(1)–C(1) N(1)–C(2)
2.5881(4) 2.6117(4) 3.2151(3) 3.2164(3) 2.5869(4) 2.6046(4) 1.314(2) 1.444(2)
S(1)#1–Ag(1)–S(1) S(1)–Ag(1)–S(2)#1 S(1)–Ag(1)–S(2) S(2)#1–Ag(1)–S(2) S(1)#1–Ag(1)–Ag(2)#2 S(2)–Ag(1)–Ag(2) Ag(2)#2–Ag(1)–Ag(2) S(2)#3–Ag(2)–S(2)#4 S(2)#3–Ag(2)–S(1) S(2)#4–Ag(2)–S(1) S(1)–Ag(2)–S(1)#1
103.918(19) 112.129(13) 113.039(13) 102.901(18) 128.041(9) 128.550(9) 180 104.287(19) 112.006(13) 112.918(13) 102.994(18)
S(1)–C(1) S(2)–C(3) N(1)–H(1N) N(2)–C(1) N(2)–H(2NA) N(2)–H(2NB) N(3)–C(3) N(3)–C(4) Bond angles S(1)–Ag(2)–Ag(1)#4 S(2)#3–Ag(2)–Ag(1) C(1)–S(1)–Ag(1) C(1)–S(1)–Ag(2) Ag(1)–S(1)–Ag(2) C(3)–S(2)–Ag(2)#2 C(3)–S(2)–Ag(1) Ag(2)#2–S(2)–Ag(1) C(1)–N(1)–C(2) C(3)–N(3)–C(4) O(2)–N(5)–O(1)
1.7296(16) 1.7308(15) 0.8800 1.321(2) 0.8800 0.8800 1.319(2) 1.443(2) 128.503(9) 127.857(9) 109.17(5) 99.79(5) 76.544(12) 111.34(5) 97.30(5) 76.406(13) 125.75(15) 125.77(15) 117.94(15)
Symmetry operators: #1: x, –1+y, z, #2: x, 1+y, z, #3: –x, –1+y, 1/2–z, #4: –x, y, 1/2–z.
Fig. 2. A view of the molecular structure of compound 1 along c-axis, showing the parallel polymeric chains separated by nitrate counter ions. 163
Fig. 3. A view of the molecular structure of compound 1 along b-axis, showing the N–H…O hydrogen bonds as dotted lines.
TABLE 3. Hydrogen Bond Distances and Angles (Å, deg) Donor–H…Acceptor
D–H
H…A
D…A
N2–H2NA…O2 N2–H2NA…O3 N1–H1N…O1 N2–H2NB…S2
0.88 0.88 0.88 0.88
2.09 2.58 2.11 2.67
2.9394 2.9273 2.9160 3.5172
D–H…A Donor–H…Acceptor 161 105 152 162
N4–H4NA…O2 N3–H3N…O1 N3–H3N…O2 N4–H4NB…S1
D–H
H…A
D…A
D–H…A
0.88 0.88 0.88 0.88
2.09 2.36 2.35 2.72
2.8556 2.9748 3.0725 3.5876
145 127 140 169
the Metu ligand binds to two silver atoms in a bridging mode, and as a result, a polymeric structure is formed. The average Ag---S---Ag bond angle is 76.475(9)°, and the average Ag…Ag distance in the four-membered Ag---S---Ag---S rings is 3.2157(2) Å. This value is considerably shorter than the sum of the van der Waals radii of two Ag(I) centers (3.44 Å), which is considered to be the upper limit of the distance for viable argentophilic interactions [31-34]. Other bond lengths observed in the title complex are comparable to those in the reported complexes [2, 7-12]. The two crystallographically independent Metu molecules bonded to the central metal atom are not co-planar, having a dihedral angle of 80.60(7)°. Within the crystal package, [Ag(Metu)2]+ units and NO3− ions are connected through hydrogen bonds. All N–H bonded hydrogen atoms are involved in hydrogen bonding. Bridging of the individual chains of edge sharing AgS4 tetrahedra occurs via these hydrogen bonds only. Both intermolecular and intramolecular hydrogen bonds are observed in the solid state structure of complex 1. These non-covalent intermolecular interactions result in a two-dimensional hydrogen bonded polymeric chain architecture as shown in Fig. 3. Hydrogen bond length details are listed in Table 3.
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SUPPLEMENTARY DATA Crystallographic data (excluding structure factors) for structure 1 have been deposited with the Cambridge Crystallographic Data Center as supplementary publication No. 691143 CCDC (1). Copies of the data can be obtained free of charge on application to CCDS, 12 Union Road, Cambridge CB2 1EZ, UK [Fax: (internat.) +44-1223/336-033; E-mail:
[email protected]]. Financial support from Pakistan Council for Science and Technology Islamabad, Pakistan is gratefully acknowledged.
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34.
S. S. Kandil, S. M. A. Katib, and N. H. M. Yarkandi, Transition Met. Chem., 32, 791-798 (2007). I. U. Khan, M. Mufakkar, S. Ahmad, et al., Acta Crystallogr., E63, m2550 (2007). P. Zoufalá, T. Rüffer, H. Lang, et al., Anal Sci.: X-ray Structure Analysis Online, 23, x219/x220 (2007). M. Hanif, S. Ahmad, M. Altaf, and H. Stoeckli-Evans, Acta Crystallogr., E63, m2594 (2007). S. v, M. K. Rauf, S. Ahmad, et al., Transition Met. Chem., 34, 197-202 (2009). V. Z. Vassileva and P. P. Petrova, Croatica Chimica Acta, 78, 295-299 (2005). M. J. Moloto, M. A. Malik, P. O’Brien, et al., Polyhedron, 22, 595-603 (2003). M. Altaf, H. Stoeckli-Evans, G. Murtaza, et al., J. Struct. Chem., 52, No. 3 (2011). T. C. Lee and E. L. Amma, J. Chem. Crystallogr., 2, 125 (1972). H. K. Fun, I. A. Razak, C. Pakawatchai, et al., Acta Crystallogr., C54, 453 (1998). M. B. Ferrari, G. G. Fava, and M. E. V. Tani, Cryst. Struct. Commun., 10, 571 (1981). C. Pakawatchai, K. Sivakumar, and H. K. Fun, Acta Crystallogr., C52, 1954 (1996). F. B. Stocker, D. Britton, and V. G. Young, Inorg. Chem., 39, 3479-3484 (2000). M. R. Udupa and B. Krebs, Inorg. Chim. Acta, 7, 271 (1973). M. R. Udupa, G. Henke, and B. Krebs, Inorg. Chim. Acta, 18, 173 (1976). E. Rodríguez-Fernández, J. L. Manzano, J. J. Benito, et al., J. Inorg. Biochem., 99, 1558-1572 (2005). R. del Campo, J. J. Criado, R. Gheorghe, et al., J. Inorg. Biochem., 98, 1307 (2004). G. Marverti, M. Cusumano, A. Ligabue, et al., J. Inorg. Biochem., 102, 699 (2008). M. Krunks, T. Leskela, and L. Niinisto, Jpn. J. Appl. Phys., 39, Suppl. 39-1, 181 (2000). T. S. Lobana, R. Sharma, E. Bermejo, and A. Castineiras, Inorg. Chem., 42, 7728 (2003). T. S. Lobana, R. Sharma, S. Mehra, et al., Inorg. Chem., 44, 1914 (2005). Stoe & Cie (2005) X-Area V1.26 & X-RED32 V1.26 Software, Stoe & Cie GmbH, Darmstadt, Germany. G. M. Sheldrick, Acta Crystallogr., A64, 112 (2008). A. L. Spek, J. Appl. Crystallogr., 36, 7 (2003). S. Ahmad, A. A. Isab, and M. Arab, Polyhedron, 21, 1267-1271 (2002). S. Ahmad, A. A. Isab, and W. Ashraf, Inorg. Chem. Comm., 5, 816-818 (2002). W. Ashraf, S. Ahmad, and A. A. Isab, Transition Met. Chem., 29, 400-404 (2002). S. Ahmad, A. A. Isab, and H. P. Perzanowski, Transition Met. Chem., 27, 782-785 (2002). A. A. Isab, Transition Met. Chem., 17, 374 (1992). E. Dubler and W. Bensch, Inorg. Chim. Acta, 125, 37 (1986). P. Pyykko, Chem. Rev., 97, 597 (1997). J. Cernak K. A. Abboud, J. Chomic, et al., Inorg. Chim. Acta, 311, 126 (2000). Y.-P. Ren, L.-S. Long, R.-B. Huang, and L.-S. Zheng, Applied Organomet. Chem., 19, 1071 (2005). P. C. Zachariadis, S. K. Hadjikakou, N. Hadjiliadis, et al., Inorg. Chim. Acta, 343, 361 (2003). 165
