Anion-dependent self-assembly of silver(I) and diaminotriazines to coordination polymers: Non-covalent bonds and role interchange between silver and hydrogen bonds

Inorg. Chem. 2008, 47, 8957-8971

Anion-Dependent Self-Assembly of Silver(I) and Diaminotriazines to

Coordination Polymers: Non-Covalent Bonds and Role Interchange

between Silver and Hydrogen Bonds

Blanca R. Manzano,*^,†Fe´lix A. Jalo´n,^†M. Laura Soriano,^†M. Carmen Carrio´n,^†M. Pilar Carranza,^†

Kurt Mereiter,^‡Ana M. Rodr´ıguez,^§Antonio de la Hoz,^†and Ana Sa´nchez-Migallo´n^†

Departamento de Qu´ımica Inorga´nica, Orga´nica y Bioqu´ımica, Facultad de Qu´ımicas, IRICA,

UniVersidad de CastillasLa Mancha, AVda Camilo Jose´ Cela, 10, E-13071 Ciudad Real, Spain,

Faculty of Chemistry, Vienna UniVersity of Technology, Getreidemarkt 9/164 SC, A-1060 Vienna,

Austria, and Departamento de Qu´ımica Inorga´nica, Orga´nica y Bioqu´ımica, Escuela Te´cnica

Superior de Ingenieros Industriales, UniVersidad de CastillasLa Mancha, AVda Camilo Jose´

Cela, 3, E-13071 Ciudad Real, Spain

Received May 31, 2008

New coordination polymers have been obtained by the self-assembly of silver salts AgX (X ) BF₄, PF₆, CF₃SO₃)

and 2,4-diamino-6-R-1,3,5-triazines L (R ) phenyl and p-tolyl) of formulas AgLX (1-6). A complex of different

stoichiometry, [Ag₃L₂(H₂O)(acetone)₂](BF₄)₃, 7 (R ) phenyl), has also been synthesized. The three-dimensional

structures of ﬁve compounds have been determined by X-ray diffraction studies. For the AgLX complexes, when

X ) BF₄and R ) phenyl or p-tolyl, chiral chains with alternating Ag and L are formed. The chains are cross-linked

by the counteranions in a three-dimensional fashion through hydrogen bonds and weak Ag · · · F interactions giving

rise to a structure with solvent-ﬁlled channels. Different and more compact structures have been found when the

counteranion is CF₃SO₃(OTf). When R ) phenyl, sheets are formed which consist of [Ag₂(OTf)₂L₂] units with

double triﬂate bridges and which contain columns of π-π stacked arenes. Hydrogen bonds connect the sheets.

When AgOTf is used and R is p-tolyl, a different and unusual ladderlike structure is obtained in which the rungs

are double asymmetric bridges consisting of the triﬂate groups bonded to Ag in κ²O,µ₂-O and κ¹O,µ₂-O fashion.

The ladders are parallel to each other and are mutually linked by N-H · · · N hydrogen bonds to give a 3D architecture.

A very similar ladderlike structure has been found for 7 but with a water molecule and a BF₄^-group acting as

bridges. The role played by the hydrogen bonds in complex 6 to form the 3-D structure is played in 7 by [Ag(acetone)₂]

fragments. The noncovalent interactions play an important role in the different solid-state 3D structures. The behavior

of the new derivatives in solution has also been analyzed. A new species has been detected at low temperatures,

and this exhibits restricted rotation of the phenyl ring.

Introduction

materials²but also exhibit structural and topological novelty

with diverse and intriguing structural motifs. The key features

that inﬂuence the architecture of self-assembled species are

the building blocks: the metal, which has a more or less

The past few decades have witnessed growing interest and

enormous progress in the ﬁeld of coordination polymers and

metal-organic framework (MOF) derivatives.¹Such materi-

als not only have potential applications as sensors, in gas

storage and catalysis, or as optoelectronic and magnetic

(1) (a) Leininger, S.; Olenyuk, B.; Stang, P. J. Chem. ReV. 2000, 100,

853–908. (b) Swiegers, G. F.; Malefetse, T. J. Chem. ReV. 2000, 100,

3483–3538. (c) Eddaoudi, M.; Moler, D. B.; Li, H.; Chen, B.; Reineke,

T. M.; O’Keeffe, M.; Yagi, O. M. Acc. Chem. Res. 2001, 34, 319–

330. (d) Ockwig, N. W.; Delgado-Friedrichs, O.; O’Keeffe, M.; Yagi,

O. M. Acc. Chem. Res. 2005, 38, 176–182. (e) Moulton, B.; Zaworotko,

M. J. Chem. ReV. 2001, 101, 1629–1658. (f) Blake, A. J.; Champness,

N. R.; Hubberstey, P.; Li, W.-S.; Withersby, M. A.; Schro¨der, M.

Coord. Chem. ReV. 1999, 183, 117–138. (g) Hong, M. Crystal Grow.

Des. 2007, 7, 10–14.

* Author to whom correspondence should be addressed. Fax: (internat.)

+ 34-926/295318. E-mail: Blanca.Manzano@uclm.es.

†

IRICA, Universidad de CastillasLa Mancha.

Vienna University of Technology.

Escuela Te´cnica Superior de Ingenieros Industriales, Universidad de

‡

§

CastillasLa Mancha.

10.1021/ic800997d CCC: $40.75  2008 American Chemical Society

Inorganic Chemistry, Vol. 47, No. 19, 2008 8957

Published on Web 09/10/2008

Manzano et al.

Scheme 1

preferred coordination environment, and the ligand, which

not only provides the donor atoms situated at speciﬁc

positions³but can also provide potential interaction sites to

generate noncovalent interactions, such as hydrogen-bond-

ing,⁴π-π stacking,⁵and anion-π and C-H · · · π interac-

tions.⁶These secondary interactions may be very important

for different aspects such as molecular recognition and

catalysisand,morespeciﬁcally,forenantioselectiveprocesses.^2g,7

In metallo-assembled architectures, the dominant factor

thatcontrolstheﬁnalsupramoleculeisusuallythemetal-ligand

interaction, and any structure adopted must fulﬁll the

requirements of the metal ion. With metals lacking strong

coordination preferences, a certain number of structures could

have similar stabilities, and weak noncovalent interactions

may have a strong effect and determine the organization of

the complex supramolecular network.^8,9The main goal of

this work was to analyze these noncovalent interactions in

order to get a deeper insight of how they can inﬂuence the

system. In order to get that, we chose the Ag(I) center as

the metal building block because it is a cation with modest

stereochemical preferences and is adaptable to different

coordination geometries.^9,10In addition, the Ag-N bonds

are not very strong. It has been reported that the energy of

a Ag-N(pyridine) bond is similar to that of a strong

hydrogen bond.¹¹It is also important to note that many

silver-ligand bonds, among them the Ag-N bond, are labile

in solution, and this gives rise to reversible processes for

supramolecularstructureformation.¹¹Thiswouldleadsthrough

a self-correction process¹²stoward the thermodynamically

more stable architecture, and it is expected that there would

also be an inﬂuence of different changes such as, for

example, the counteranion or small variations in the ligands.

Many examples of silver(I) coordination polymers have been

described, and these include linear chains, zigzag chains,

helices, ladders, and two- and three-dimensional networks

of different natures.^1f,11,13Discrete species of distinct nucle-

arity have also been reported.^9,14

(2) (a) Holliday, B. J.; Mirkin, C. A. Angew. Chem., Int. Ed. 2001, 40,

2022–2043. (b) McCleverty, J. A.; Ward, M. D. Acc. Chem. Res. 1998,

31, 842–851. (c) Gamez, P.; Hoog, P. D.; Roubeau, O.; Lutz, M.;

Driessen, W. L.; Spek, A. L.; Reedijk, J. Chem. Commun. 2002, 1488–

1489. (d) Hong, M. C.; Zhao, Y. J.; Su, W.; Cao, R.; Fujita, M.; Zhou,

Z. Y.; Chan, A. S. C. Angew. Chem., Int. Ed. 2000, 39, 2468–2470.

(e) Yaghi, O. M.; Li, H.; Groy, T. L. Inorg. Chem. 1997, 36, 4292–

4293. (f) Cui, Y.; Ngo, H. L.; Lin, W. B. Inorg. Chem. 2002, 41,

1033–1035. (g) Wu¨rthner, F.; You, C.-C.; Saha-Mo¨ller, C. R. Chem.

Soc. ReV. 2004, 33, 133–146. (h) Pri-Bar, I.; Koresh, J. E. J. Mol.

Catal. A: Chem. 2000, 156, 173. (i) Hofmeier, H.; Schubert, U. S.

Chem. Soc. ReV. 2004, 33, 373–399. (j) Rudkevich, D. M. Angew.

Chem., Int. Ed. Engl. 2004, 43, 558–571. (k) Mulfort, K. L.; Hupp,

J. T. J. Am. Chem. Soc. 2007, 129, 9604–9605. (l) Lin, X.; Blake,

A. J.; Wilson, C.; Sun, X. Z.; Champness, N. R.; George, M. W.;

Hubberstey, P.; Mokaya, R.; Schro¨der, M. J. Am. Chem. Soc. 2006,

128, 10745–10753. (m) Jia, J.; Lin, X.; Wilson, C.; Blake, A. J.;

Champness, N. R.; Hubberstey, P.; Walker, G.; Cussena, E. J.;

Schro¨der, M. Chem. Commun. 2007, 840–842. (n) Kitagawa, S.;

Kitaura, R.; Noro, S.-I. Angew. Chem., Int. Ed. 2004, 43, 2334–2375.

(o) Janiak, C. Dalton Trans 2003, 2781–2804. (p) Uemura, K.;

Matsuda, R.; Kitagawa, S. J. Solid. State Chem. 2005, 178, 2420–

2429. (q) Dobrawa, R.; Wu¨rthner, F. J. Polym. Sci., Part A: Polym.

Chem. 2005, 43, 4981–4995.

(3) (a) Olenyuk, B.; Fechtenko¨tter, A.; Stang, P. J. J. Chem. Soc., Dalton

Trans. 1998, 1707–1728. (b) Stang, P. J. Chem.sEur. J. 1998, 4, 19–

27. (c) Holliday, B. J.; Mirkin, C. A. Angew. Chem., Int. Ed. 2001,

40, 2022–2043. (d) Fujita, M.; Umemoto, K.; Yoshizawa, M.; Fujita,

N.; Kusukawa, T.; Biradha, K. Chem. Commun. 2001, 509–518. (e)

Papaefstathiou, G. S.; MacGillivray, L. R. Coord. Chem. ReV. 2003,

246, 169–196. (f) Baxter, P. N. M. In ComprehensiVe Supramolecular

Chemistry; Atwood, J. L., Davies, J. E. D., MacNicol, D. D., Vo¨gtle,

F., Lehn, J.-M., Eds.; Pergamon: Oxford, U. K.; Vol. 9, pp 165-211.

Also see Constable, E. C. in the same reference, pp 213-252, and

Fujita, M. in the same reference, p. 253-282. (g) Ward, M. D. Annu.

Rep. Prog. Chem. Sect. A 2001, 97, 293–392.

As organic synthons, we decided to use 2,4-diamino-6-

R-1,3,5-triazines (see Scheme 1), mainly because they could

give rise to different types of secondary interactions. It has

been reported that the s-triazine ring constitutes a remarkable

unit for generating supramolecular interactions, namely,

coordination bonding, hydrogen bonding, electrostatic and

charge-transfer attractions, and aromatic-stacking interac-

(4) (a) Jeffrey, G. A. An Introduction to Hydrogen Bonding, Oxford

University Press, New York, 1997. (b) Beatty, A. M. Coord. Chem.

ReV. 2003, 246, 131–143. (c) Awaleh, M. O.; Badia, A.; Brisse, F.

Cryst. Growth Des. 2005, 5, 1897–1906. (d) Braga, D.; Grepioni, F.;

Desiraju, G. R. Chem. ReV. 1998, 98, 1375–1405.

(5) (a) Janiak, C. Dalton Trans. 2000, 3885–3896, and references therein.

(b) Ponzini, F.; Zagha, R.; Hardcastle, K.; Siegel, J. S. Angew. Chem.,

Int. Ed. 2000, 39, 2323–2325. (c) Kim, J. L.; Nikolov, D. B.; Burley,

S. K. Nature 1993, 365, 520–527. (d) Kim, Y.; Geiger, J. H.; Hahn,

S.; Sigler, P. B. Nature 1993, 365, 512–520.

(6) (a) Nishio, M.; Umezawa, Y.; Hirota, M.; Takeuchi, Y. Tetrahedron

1995, 51, 8665–8701. (b) Takahashi, H.; Tsuboyama, S.; Honda, K.;

Nishio, M. Tetrahedron 2000, 56, 6185–6191. (c) Re, S.; Nagase, S.

Chem. Commun. 2004, 658–659.

(7) See for example: (a) Pri-Bar, I.; Koresh, J. E. J. Mol. Catal. A, Chem.

2000, 156, 173–180. (b) van Leeuwen, P. W. N. M.; Roobeek, C. F.;

Frijns, J. H. G.; Orpen, A. G. Organometallics 1990, 9, 1211–1222.

(c) Breit, B.; Seiche, W. J. Am. Chem. Soc. 2003, 125, 6608–6609.

(d) Yoshizawa, M.; Tamura, M.; Fujita, M. Science 2006, 312, 251–

254. (e) Wu, C.-D.; Hu, A.; Zhang, L.; Lin, W. J. Am. Chem. Soc.

2005, 127, 8940–8941. (f) Nishio, M.; Umezawa, Y.; Hirota, M.;

Takeuchi, Y. Tetrahedron 1995, 51, 8665–8701.

(8) Chen, C.-L.; Su, C.-Y.; Cai, Y.-P.; Zhang, H.-X.; Xu, A.-W.; Kang,

B.-S.; zur Loye, H.-C. Inorg. Chem. 2003, 42, 3738–3750.

(9) (a) Hannon, M. J.; Painting, C. L.; Plummer, E. A.; Childs, L. J.;

Alcock, N. W. Chem.sEur. J. 2002, 8, 2225–2238. (b) Price, J. R.;

Lan, Y.; Jameson, G. B.; Brooker, S. Dalton Trans 2006, 1491–1494.

(10) (a) Fielden, J.; Long, D.-L.; Slawin, A. M. Z.; Ko¨gerler, P.; Cronin,

L. Inorg. Chem. 2007, 46, 9090–9097. (b) Reger, D. L.; Semeniuc,

R. F.; Smith, M. D. Eur. J. Inorg. Chem. 2003, 3480–3494. (c)

Blondeau, P.; van der Lee, A.; Barboiu, M. Inorg. Chem. 2005, 44,

5649–5693.

(11) Khlobystov, A. N.; Blake, A. J.; Champness, N. R.; Lemenovskii,

D. A.; Majouga, A. G.; Zyk, N. V.; Schro¨der, M. Coord. Chem. ReV.

2001, 222, 155–192.

(12) Stadler, A.-M.; Kyritsakas, N.; Vaughan, G.; Lehn, J.-M. Chem.sEur.

J. 2007, 13, 59–68.

(13) Chen, C.-L.; Kang, B.-S.; Su, C.-Y. Aust. J. Chem. 2006, 59, 3–18.

(14) (a) Ruben, M.; Rojo, J.; Romero-Salguero, F. J.; Uppadine, L. H.;

Lehn, J.-M. Angew. Chem., Int. Ed. 2004, 43, 3644–3662. (b) Baxter,

P. N. W.; Lehn, J.-M.; Baum, G.; Fenske, D. Chem.sEur. J. 2000, 6,

4510–4517.

8958 Inorganic Chemistry, Vol. 47, No. 19, 2008

Self-Assembly of SilWer(I) and Diaminotriazines

tions.¹⁵The presence of the amino groups could enhance

the formation of hydrogen bonds either with the nitrogen

atoms of the ring or with other atoms such as, for example,

those of the counteranions. The ligands also contain an

aromatic substituent in position 6 of the triazine ring, and

this could play different roles in the structure and packing

of the new compounds through, for example, stacking or

hydrophobic interactions. The structures of some of these

types of triazine derivatives have been described previously

(R ) 4-pyridyl,¹⁶phenyl,¹⁷1-piperidino,¹⁷and 1-phe-

nylpyrazol-3-yl¹⁷) in addition to that of 6,6′,6′′-(1,3,5-

phenylene)tris-1,3,5-triazine-2,4-diamine.¹⁸The supramo-

lecular structure is strongly dependent on the nature of the

substituent in position 6. In these structures the molecules

are connected through bidirectional N-H · · · N hydrogen-

bonded pairs to form ribbons or sheets that are linked to

give a 3D network. The interaction with other organic entities

that contain complementary functional groups to form triple

hydrogen bonds (DAD/ADA, D ) donor of hydrogen, A )

acceptor of hydrogen) has been described,¹⁹but their

coordination chemistry has been scarcely explored. Several

derivatives in which the diaminotriazine ligand is coordinated

by one nitrogen atom of the ring have been described.²⁰

However, examples involving coordination of the amino

nitrogens have not been reported. This is not unexpected

considering the acidity of the electron-poor triazine ring.

Consequently, the atoms that should be able to coordinate

to the metallic center are the three nitrogen atoms of the

ring, and according to symmetry arguments, there are two

types of these. The coordination of two of these atoms to

linear silver cations will give rise to the formation of zigzag

chains.

although the triﬂate anion has sometimes been considered

as a poor ligand, its coordination chemistry is now quite

broad,²¹and many different types of coordination from

monodentate,²²bidentate,²³and up to µ₄

and µ₅are

24,25

25

known. The ability of the counterions to form hydrogen

bonds was also expected to be important, and once again,

the triﬂate counteranion is expected to have a higher tendency

to form such interactions than the other anions.^26,27

Experimental Section

Materials and Methods. All reactions were carried out under a

nitrogen atmosphere using standard Schlenk techniques. All solvents

were freshly distilled. AgX (X ) BF₄, PF₆, and CF₃SO₃) and Toldat

were purchased from Aldrich and used without further puriﬁcation.

The ligand Phdat was prepared by a literature method.¹⁷Elemental

analyses were performed with a Thermo Quest FlashEA 1112

microanalyzer. IR spectra were recorded as Nujol mulls with a

Perkin-Elmer PE 883 IR (4000-400 cm^-1) or with an ATR system

in IRPRESTIGE-21 Shimadzu (4000-700 cm^-1) spectrometers.

The mass spectrometery measurements were made with a matrix-

assisted laser desorption ionization-time of ﬂight (MALDI-TOF)

Applied Biosystems Voyager DE STR or with a Q-q-TOF hybrid

analyzer with an electrospray ionization source (QStar Elite Applied

Biosystems spectrometers). X-ray powder patterns were recorded

with Bruker D8 Advance and Panalytical X’Pert MPD diffracto-

meters with Cu KR radiation. Thermogravimetric analysis (TGA)

and differential thermal analysis (DTA) were made with an ATD-

TG SETARAM apparatus with a 92-16.18 graphite oven and CS32

controller. The analyses were made with a heating rate of 5 °C/

min, under an argon ﬂux in a platinum crucible. ¹H, ¹³C{¹H}, and

¹⁹F NMR spectra were recorded on a Varian Unity 300, a Varian

Gemini 400, and an Inova 500 spectrometer. Chemical shifts (ppm)

are relative to tetramethylsilane (¹H, ¹³C NMR) and CFCl₃(¹⁹F

NMR). Coupling constants (J) are in Hertz. The nuclear Overhauser

effect difference spectra were recorded with a 5000 Hz spectrum

width, an acquisition time of 3.27 s, a pulse width of 90°, a

relaxation delay of 4 s, an irradiation power of 5 × 10 dB, and a

number of scans of 240. For ¹H-¹³C gradient-selected heteronuclear

multiple quantum coherence (g-HMQC) spectra, the standard Varian

pulse sequences were used (VNMR 6.1 C software). The spectra

were acquired using 7996 Hz (¹H) and 25133.5 Hz (¹³C) widths;

16 transients of 2048 data points were collected for each of the

256 increments. For variable-temperature spectra, the probe tem-

perature ((1 K) was controlled by a standard unit calibrated with

a methanol reference. The carbon resonances are singlets. o, m,

Taking into account the previous considerations on the

two building blocks, we consider that our system is very

well suited for the study of the effect that the noncovalent

interactions have on the ﬁnal architecture. We were also

interested in studying the impact of the counteranion, and

-

we introduced PF₆, BF₄, and CF₃SO₃(OTf) into the

system. We envisaged that the coordinating ability of the

counterion could play a very important role. In this sense,

-

PF₆and BF₄will not tend to coordinate easily, and

(15) (a) Gamez, P.; Reedijk, J. Eur. J. Inorg. Chem. 2006, 29–42. (b)

Mooibroek, T. J.; Gamez, P. Inorg. Chim. Acta 2007, 360, 381–404.

(c) Ohmori, O.; Kawano, M.; Fujita, M. Cryst. Eng. Commun. 2005,

7, 255–259. (d) Yamauchi, Y.; Yoshizawa, M.; Fujita, M. J. Am. Chem.

Soc. 2008, 130, 5832–5833.

(16) Chan, C.-W.; Mingos, M. P.; White, A. J. P.; Williams, D. J.

Polyhedron 1996, 15, 1753–1767.

(17) D´ıaz-Ortiz, A.; Elguero, J.; Foces-Foces, C.; de la Hoz, A.; Moreno,

A.; Mateo, M. C.; Sa´nchez-Migallo´n, A.; Valiente, G. New. J. Chem.

2004, 28, 952–958.

(18) Helzy, F. H.; Maris, T.; Wuest, J. D. Cryst. Growth Des. 2008, 8,

1547–1553.

(19) (a) Bishop, M. M.; Lindoy, L. F.; Skelton, B. W.; White, A. H.

J. Chem. Soc., Dalton Trans. 2002, 377–382. (b) Manzano, B. R.;

Jalo´n, F. A.; Soriano, M. L.; Rodr´ıguez, A. M.; de la Hoz, A.; Sa´nchez-

Migallo´n, A. Cryst. Growth Des. 2008, 8, 1585–1594.

(20) (a) Deak, A.; Kalman, A.; Parkanyi, L.; Haiduc, I. Acta Crystallogr.,

Sect. B 2001, 57, 303–310. (b) Aoki, K.; Inaba, M.; Teratani, S.;

Yamazaki, H.; Miyashita, Y. Inorg. Chem. 1994, 33, 3018–3020. (c)

Drew, M. G. B.; Hill, C.; Hudson, M. J.; Iveson, P. B.; Madic, C.;

Youngs, T. G. A. Dalton Trans. 2004, 244–251. (d) Dorta, R.; Stoeckli-

Evans, H.; Bodensieck, U.; Su¨ss-Fink, G. J. Organomet. Chem. 1998,

553, 307–315.

(21) (a) Lawrance, G. A. Chem. ReV. 1986, 86, 17–33. (b) Coˆte´, A. P.;

Shimizu, G. K. H. Coord. Chem. ReV. 2003, 245, 49–64.

(22) See, for example: (a) Venkataraman, D.; Gardner, G. B.; Lee, S.;

Moore, J. S. J. Am. Chem. Soc. 1995, 117, 11600–11601. (b) Gardner,

G. B.; Venkataraman, D.; Moore, J. S.; Lee, S. Nature 1995, 374,

792–795. (c) Venkataraman, D.; Lee, S.; Moore, J. S.; Zhang, P.;

Hirsch, K. A.; Gardner, G. B.; Covey, A. C.; Prentice, C. L. Chem.

Mater. 1996, 8, 2030–2040.

(23) See, for example: (a) Hirsch, K. A.; Wilson, S. R.; Moore, J. S. J. Am.

Chem. Soc. 1997, 119, 10401–10412. (b) Hirsch, K. A.; Wilson, S. R.;

Moore, J. S. Inorg. Chem. 1997, 36, 2960–2968.

(24) Lu, X. L.; Leong, W. K.; Hor, T. S. A.; Goh, L. Y. J. Organomet.

Chem. 2004, 689, 1746–1756.

(25) Coˆte´, A. P.; Ferguson, M. J.; Khan, K. A.; Enright, G. D.; Kulynych,

A. D.; Dalrymple, S. A.; Shimizu, G. K. H. Inorg. Chem. 2002, 41,

287–292.

(26) Reger, D. L.; Watson, R. P.; Gardinier, J. R.; Smith, M. D. Inorg.

Chem. 2004, 43, 6609–6619.

(27) Reger, D. L.; Semeniuc, R. F.; Rassolov, V.; Smith, M. D. Inorg.

Chem. 2004, 43, 537–554.

Inorganic Chemistry, Vol. 47, No. 19, 2008 8959

Manzano et al.

and p stand for ortho, meta, and para, respectively. When numbering

the protons or carbons, the primes are used for the tolyl substituent.

X-Ray Structure Determination for 2, 3, 5, 6, and 7. The

method for the crystallization of compounds 2, 3, 5, and 6 was

solvent counter diffusion of the starting reagents and consisted of

the use of three layers of different solvents put in a screw-cap tube

according to their density. The tube was charged under an inert

atmosphere. The lower layer consisted of a solution of the ligand

in the solvent with the largest density. A second layer was put in

without any reagent in it, and ﬁnally the upper layer contained the

AgX salt dissolved in the solvent of lowest density (see each

complex for the details).

X-ray data for 2, 3, 5, 6, and 7 were collected on Bruker APEX

CCD area detector diffractometers (SMART APEX for 5 and 7,

X8 APEX II for the rest) with graphite monochromated Mo KR

radiation (λ ) 0.71073 Å) and ω-scan frames covering complete

spheres of the reciprocal space. The frame data were integrated

using the program SAINT,²⁸and an absorption correction was

performed with the program SADABS.²⁹The software package

SHELXTL version 6.10³⁰was used for space group determination,

structure solution, and reﬁnement by full-matrix least-squares

methods based on F². All non-hydrogen atoms were reﬁned with

anisotropic thermal parameters. Hydrogen atoms were placed in

calculated positions and reﬁned as riding. For 2 and 5, the disordered

solvent was squeezed with the program PLATON.³¹

1626, 1581, 1530 and 1505 (CdN) and (CdC), 1020 and 523 (BF₄).

¹H NMR (300 MHz, [D₆]acetone, 25 °C): δ 8.26 (d, J ) 7.1 Hz,

2H, H_o), 7.50 (t, J ) 7.3 Hz, 2H, H_m), 7.59 (t, J ) 7.5 Hz, 1H,

H_p), 7.10 ppm (bs, 4H, NH₂). ¹⁹F NMR (282 MHz, [D₆]acetone,

25 °C): δ -151.9 ppm (s, BF₄). MALDI-TOF MS: m/z 294 [AgL]⁺

(100%), 481 [AgL₂]⁺(36.9%), 590 [Ag₂L₂]⁺(7.2%). Elem anal.

calcd (%) for C₉H₉AgBF₄N₅(381.9): C, 28.31; H, 2.38; N, 18.34.

Found: C, 28.29; H, 2.58; N, 18.50.

Synthesis of [Ag(Phdat)(OTf)]_n, 3. Phdat (20.6 mg, 0.11 mmol)

and AgOTf (28.3 mg, 0.11 mg) were mixed in 30 mL of THF at

room temperature. Immediately, a white suspension appeared. After

12 h of stirring, the suspension was concentrated under a vacuum,

separated from the solution by ﬁltration, washed with a 1:1 mixture

of CH₂Cl₂and Et₂O (2 × 20 mL), and dried. Complex 3 is obtained

as a white powder (44.8 mg, 92%). Colorless crystals for X-ray

diffraction were obtained with the following three layers: CH₂Cl₂/

THF with the ligand, neat acetone, and Et₂O with AgOTf. IR (Nujol

mull): ν_max/cm^-13344 (NH₂), 1646, 1561, 1541 and 1512 (CdN)

1

and (CdC), 1000 (CH_phenyl), 1296, 1175, 818 and 630 (OTf). H

NMR (300 MHz, [D₆]acetone, 25 °C): δ 8.29 (d, J ) 7.3 Hz, 2H,

H_o), 7.49 (t, J ) 7.1 Hz, 2H, H_m), 7.54 (t, J ) 7.3 Hz, 1H, H_p),

7.02 ppm (bs, 4H, NH₂). ¹⁹F NMR (282 MHz, [D₆]acetone, 25 °C):

δ -80.2 ppm (s, OTf). MALDI-TOF MS: m/z 294 [AgL]⁺(100%),

481 [AgL₂]⁺(37.1%), 443 [AgL(OTf)]⁺(3.5%). Elem anal. calcd

(%) for C₁₀H₉AgF₃N₅O₃S (444.1): C, 27.04; H, 2.04; N, 15.77.

Found: C, 27.15; H, 2.13; N, 15.54.

Synthesis of [Ag(Toldat)(PF₆)]_n, 4. Toldat (16.1 mg, 0.08 mmol)

was made to react with AgPF₆(20.2 mg, 0.08 mmol) in THF (30

mL) at room temperature. A colorless solution was formed, and

after 2 h, it was concentrated, and a white suspension appeared.

The product was ﬁltrated, washed with Et₂O (3 × 10 mL), and

dried under a vacuum. Complex 4 was obtained as a white solid

(29.7 mg, 82%). IR (Nujol mull): ν_max/cm^-13348 (NH₂), 1622,

1564 and 1510 (CN) and (CdC), 829 and 556 (PF₆).¹H NMR (300

MHz, [D₆]acetone, 25 °C): δ 8.21 (d, J ) 8.2 Hz, 2H, H-2′,6′),

7.26 (d, J ) 8.2 Hz, 2H, H-3′,5′), 6.52 (bs, 4H, NH₂), 2.38 ppm (s,

3H, CH₃). ¹⁹F NMR (282 MHz, [D₆]acetone, 25 °C): δ -73.1 ppm

(d, J ) 708 Hz, PF₆). MALDI-TOF MS: m/z 308 [AgL]⁺(100%),

509 [AgL₂]⁺(33.5%), 616 [Ag₂L₂]⁺(7.0%). Elem anal. calcd (%)

for C₁₀H₁₁AgF₆N₅P (454.1): C, 26.45; H, 2.44; N, 15.42. Found:

C, 26.41; H, 2.50; N, 15.64.

Synthesis of [Ag(Phdat)(PF₆)]_n·(CH₂Cl₂)_2n, 1. Phdat (16.8 mg,

0.09 mmol) and AgPF₆(22.8 mg, 0.09 mmol) were mixed in 30

mL of CH₂Cl₂at room temperature. The colorless solution was

stirred over 12 h, and after that the solution was evaporated to

dryness. While the solvent was removed under a vacuum, a solid

was progressively appearing. The product was washed with a 1:1

mixture of CH₂Cl₂and Et₂O (2 × 25 mL) and dried. Complex 1

was obtained as a white powder (35.9 mg, 91%). IR (Nujol mull):

ν

_max/cm^-13382 (NH₂), 1626, 1581, 1535 and 1506, (CdN) and

1

(CdC); 838 and 557 (PF₆). H NMR (300 MHz, [D₆]acetone, 25

°C): δ 8.27 (d, J ) 7.0 Hz, 2H, H_o), 7.58 (t, J ) 7.3 Hz, 2H, H_m),

7.50 (t, J ) 7.3 Hz, 1H, H_p), 7.07 ppm (bs, 4H, NH₂). ¹⁹F NMR

(282 MHz, [D₆]acetone, 25 °C): δ -73.1 ppm (d, J ) 707 Hz,

PF₆). MALDI-TOF MS: m/z: 294 [AgL]⁺(100%), 481 [AgL₂]⁺

(36.1%), 590 [Ag₂L₂]⁺(7.6%). Elem anal. calcd (%) for

C₉H₉AgF₆N₅P·2(CH₂Cl₂) (609.9): C, 21.66; H, 2.15; N, 11.48.

Found: C, 21.30; H, 1.96; N, 12.00 (CH₂Cl₂content proven by

NMR).

Synthesis of [Ag(Toldat)(BF₄)]_n, 5. Toldat (38.2 mg, 0.19 mmol)

and AgBF₄(37.0 mg, 0.19 mmol) were mixed in THF (30 mL) at

room temperature, and a white suspension was formed. After 2 h,

the precipitate was ﬁltered off and washed with Et₂O (3 × 10 mL),

then dried under a vacuum. Complex 5 was obtained as a white

solid (65.3 mg, 87%). Colorless single crystals of 5 for the X-ray

diffraction were obtained after slow diffusion of the reactants using

the following three layers: CH₂Cl₂/THF with the ligand, neat THF,

and acetone/pentane with AgBF₄. IR (Nujol mull): ν_max/cm^-13371

(NH₂), 1626, 1581, 1530 and 1505 (CdN) and (CdC), 1020 and

Synthesis of [Ag(Phdat)(BF₄)]_n, 2. Phdat (20.6 mg, 0.11 mmol)

and AgBF₄(21.4 mg, 0.11 mmol) were mixed in 30 mL of

tetrahydrofuran (THF) at room temperature, and a white suspension

appeared. After 12 h of stirring, the white solid of 2 was

concentrated under a vacuum, separated from the solution by

ﬁltration, washed with a 1:1 mixture of CH₂Cl₂and Et₂O (2 × 20

mL), and dried. Complex 2 was obtained as a white powder (37.4

mg, 89%). Colorless crystals for X-ray diffraction were obtained

with the following three layers: CH₂Cl₂with the ligand, neat THF,

and acetone with AgBF₄. IR (Nujol mull): ν_max/cm^-13374 (NH₂),

1

522 (BF₄). H NMR (300 MHz, [D₆]acetone, 25 °C): δ 8.15 (d, J

) 8.3 Hz, 2H, H-2′,6′), 7.30 (d, J ) 8.3 Hz, 2H, H-3′,5′), 7.04 (bs,

4H, NH₂), 2.39 (s, 3H, CH₃). ¹³C {¹H} NMR (75 MHz, [D₆]acetone,

25 °C): δ 170.1 (C-2,4), 165.4 (C-6), 129.8 (C-3′,5′), 127.5 (C-

2′,6′), 143.0 (C-6′), 135.6 (C-4′), 20.9 ppm (CH₃). ¹⁹F NMR (282

MHz, [D₆]acetone, 25 °C): δ -151.5 (s, BF₄). ESI-TOF MS: m/z

107 [Ag]⁺(20.8%), 202 [L]⁺(100%), 308 [AgL]⁺(92.1%), 326

[AgL(H₂O)]⁺(16.85%), 509 [AgL₂]⁺(35.1%), 616 [Ag₂L₂]⁺

(7.6%). Elem anal. calcd (%) for C₁₀H₁₁AgBF₄N₅(395.9): C, 30.34;

H, 2.80; N, 17.69. Found: C, 30.28; H, 3.01; N, 17.87.

(28) Area-Detector Integration Program: SAINT+, v. 7.12a; Bruker-Nonius

AXS: Madison, WI, 2004.

(29) A Program for Empirical Absorption Correction: Sheldrick, G. M.

SADABS, version 2004/1; University of Go¨ttingen: Go¨ttingen, Ger-

many, 2004.

(30) (a) Structure Determination Package: SHELXTL-NT, version 6.12;

Bruker-Nonius AXS: Madison, WI, 2001. (b) SHELXS-97, Program

for Structure Solution: Sheldrick, G. M. Acta Crystallogr., Sect. A

1990, 46, 467. (c) Program for Crystal Structure Reﬁnement: Sheldrick,

G. M. SHELXL-97; Universita¨t Go¨ttingen: Go¨ttingen, Germany, 1997.

(31) A multipurpose crystallographic tool: Spek, A. L. PLATON; Utrecht

University: Utrecht, The Netherlands, 2007.

Synthesis of [Ag(Toldat)(OTf)]_n, 6. Toldat (22.1 mg, 0.11

mmol) and AgOTf (28.3 mg, 0.11 mmol) were mixed in acetone

8960 Inorganic Chemistry, Vol. 47, No. 19, 2008

Self-Assembly of SilWer(I) and Diaminotriazines

Scheme 2

metry. In the case of 7, four bands are observed in the

ν(B-F) region around 1000 cm^-1.

We registered the mass spectra for complexes 1-6

(MALDI-TOF for 1-4 or ESI-TOF for 5 and 6, see the

Experimental Section for detailed data). For all derivatives,

peaks corresponding to the fragments [AgL]⁺and [AgL₂]⁺

were observed. The fragment [Ag₂L₂]⁺was also observed

for all complexes except for those containing triﬂate groups

where the fragments [AgL(OTf)]⁺(3) or [Ag₂L₂(OTf)]⁺(6)

were detected. This is probably a consequence of the higher

coordinating ability of this anion. When the ESI-TOF

technique was used, peaks corresponding to [Ag]⁺and [L]⁺

were also present.

(20 mL) at room temperature, and a white suspension was formed.

The reaction was allowed to proceed for 24 h without any further

changes. The precipitate was ﬁltered and washed with Et₂O (2 ×

10 mL) and then dried under a vacuum. Complex 6 was obtained

as a white solid (45.3 mg, 90%). Colorless single crystals of 6 for

X-ray diffraction were obtained after slow diffusion of the reactants

using the following three layers: CH₂Cl₂/THF with the ligand, neat

THF, and acetone/pentane with AgOTf. IR (ATR): ν_max/cm^-13329

(NH₂), 1643, 1612, 1574 and 1530 (CdN) and (CdC); 1299, 1183

X-Ray Structure Determination. The structures of

complexes 2, 3, 5, 6, and 7 were determined by X-ray

diffraction studies. The crystallographic data are given in

Table 1. A selection of bond distances and angles are

gathered in Table 2 for complexes 2 and 5 and in Table 3

for complexes 3, 6, and 7. It was not possible to obtain

1

and 808 (OTf). H NMR (300 MHz, [D₆]acetone, 25 °C): δ 8.18

(d, J ) 8.2 Hz, 2H, H-2′,6′), 7.29 (d, J ) 8.2 Hz, 2H, H-3′,5′),

6.91 (bs, 4H, NH₂), 2.39 (s, 3H, CH₃). ¹³C {¹H} NMR (75 MHz,

[D₆]acetone, 25 °C): δ 128.3 (C-2′,6′), 129.3 (C-3′,5′), 142.6 (C-

6′), 20.9 ppm (CH₃). ¹⁹F NMR (282 MHz, [D₆]acetone, 25 °C): δ

-79.1 ppm (s, OTf). ESI-TOF MS: m/z 107 [Ag]⁺(17.3%), 202

[L]⁺(36.9%), 308 [AgL]⁺(100%), 509 [AgL₂]⁺(35.7%), 767

[Ag₂L₂(OTf)]⁺(2.6%). Elem anal. calcd (%) for C₁₁H₁₁AgF₃N₅O₃S

(458.2): C, 28.84; H, 2.42; N, 15.3. Found: C, 28.68; H, 2.38; N,

14.98.

Synthesis of [Ag₃(Phdat)₂(OH₂)(acetone)₂(BF₄)₃]_n, 7. To a

solution of Phdat (20.6 mg, 0.11 mmol) in 3 mL of acetone was

added solid AgBF₄(41.6 mg, 0.21 mmol). After the solution was

stirred, diethylether was allowed to diffuse over three days, and

monocrystals of 7 as colorless plates appeared. They were ﬁltered,

washed with diethyl ether (2 × 1 mL), and dried with a nitrogen

ﬂow. IR (ATR): ν_max/cm^-13396 and 3327 (NH₂) and (OH₂), 1651

(OdCMe₂), 1581, 1556 and 1518 (CdN) and (CdC), 1061, 1042,

1020 and 978 ν(B-F). Elem anal. calcd (%) for

C₂₄H₃₂Ag₃B₃F₁₂N₁₀O₃(1092.6): C, 26.38; H, 2.95; N, 12.82. Found:

C, 26.72; H, 2.84; N, 12.44.

-

crystals of the PF₆derivatives.

Complexes 2 and 5. Complexes [Ag(Phdat)](BF₄) and

[Ag(Toldat)](BF₄) (2 and 5) were found to be isostructural,

both crystallizing in the orthorhombic space group I2₁2₁2₁

with related unit cell dimensions. The structures of both

compounds are very similar, and therefore only the phenyl

compound is shown in the ﬁgures. A polymeric chain is

formed, and this extends along the a axis and consists of

{Ag(L)} fragments (Figure 1). Silver has an approximately

linear coordination geometry [N1-Ag1-N1A angle of

179.5(3)° for 2 and 171.1(1)° for 5] and is bonded to the

triazine nitrogen atoms N¹and N⁵(see Scheme 1 for atom

numbering). The phenyl rings are practically perfectly ﬂat

(aplanarity <0.002 Å), but the triazine rings are remarkably

aplanar and twisted, showing root mean square (rms)

aplanarities of 0.056 Å (2) and 0.052 Å (5). In both

complexes, the two rings of the ligand are not coplanar

[interplanar angles of 39.9(4)° for 2 and 40.8(2)° for 5].

Although not unprecedented in amino-triazine-metal

systems,^20a,32it is interesting to note that the silver centers

are not in the same plane as the triazine rings: the distances

to the plane are (0.92(1) Å for 2 and (0.845(5) Å for 5.

For a speciﬁc triazine ring, the two silver atoms bonded to

it deviate in opposite directions. This deviation means that

consecutive triazine rings are mutually inclined at angles of

53.8° in 2 and 59.6° in 5 and that the Ag-triazine chains

have a helical character (see Figure 1a,b, where the sinusoidal

character of the chain in two orthogonal planes can be

observed). In fact, the analyzed crystals are chiral as a

consequence of the fact that only P chains were found for

both complexes (see Scheme S1, Supporting Information;

the pitch, constituted by two silver centers and two ligands,

is 12.02 Å in complex 2 and 11.68 Å in complex 5). The

triazine molecules exhibit a head-to-tail disposition.

Results and Discussion

Synthesis and Characterization. The different aminot-

riazine ligands were reacted with silver(I) salts in a metal-

to-ligand ratio of 1:1 (see Scheme 2).

The products were obtained in high yields. According to

the elemental analysis, the stoichiometry of the products 1-6

is AgLX (in the case of 1, crystallization solvent is also

included). After a ﬁnding of the NMR studies (see below),

we crystallized a AgBF₄/Phdat mixture in a 2:1 ratio. Crystals

of a new product, 7, of stoichiometry [Ag₃L₂(H₂O)-

(acetone)₂(BF₄)₃] were obtained from acetone/diethyl ether.

The water of this compound must come from the silver salt.

The IR spectra of the new compounds show bands corre-

sponding to the ν(N-H), ν(CdN), or ν(CdC) vibrations.

The presence of the counteranions was also corroborated

from the vibration spectra (see the Experimental Section).

In the case of the BF₄^-complexes 2 and 5, the ν(B-F) band

is split, a fact that indicates the existence of some kind of

interaction involving the anion that decreases the T_dsym-

(32) (a) Zhu, H.; Yu, Z.; You, X.; Hu, H.; Huang, X. J. Chem. Cryst. 1999,

29, 239–242. (b) Goodgame, D. M. L.; Hussain, I.; White, A. J. P.;

Williams, D. J. J. Chem. Soc., Dalton Trans. 1999, 2899–2900. (c)

Chen, Ch.; Yeh, Ch.-W.; Chen, J.-D. Polyhedron 2006, 25, 1307–

1312.

Inorganic Chemistry, Vol. 47, No. 19, 2008 8961

Manzano et al.

Table 1. Crystal Data and Structure Reﬁnement for 2·solv, 5·solv, 3, 6, and 7

[Ag(Phdat)(BF₄)]_n·

solv, 2·solv

[Ag(Toldat)(BF₄)]_n·

solv, 5·solv

[Ag(Phdat)

(OTf)]_n, 3

[Ag(Toldat)

(OTf)]_n, 6

[Ag₃(Phdat)₂(H₂O)

(Me₂CO)₂(BF₄)₃]_n, 7

empirical formula

F_w

C₉H₉AgBF₄N₅

381.89

C₁₀H₁₁AgBF₄N₅

395.91

C₁₀H₉AgF₃N₅O₃S

444.15

C₁₁H₁₁AgF₃N₅O₃S

458.18

C₂₄H₃₂Ag₃B₃F₁₂N₁₀O₃

1092.64

a

T (K)

180(2)

173(2)

180(2)

100(2)

cryst size (mm³)

cryst syst

space group

Z

0.34 × 0.22 × 0.18 0.53 × 0.37 × 0.31 0.63 × 0.28 × 0.19 0.44 × 0.08 × 0.04

0.55 × 0.32 × 0.03

monoclinic

C2/c (no. 15)

4

orthorhombic

I2₁2₁2₁(no. 24)

4

orthorhombic

I2₁2₁2₁(no. 24)

4

monoclinic

P2₁/c (no. 14)

8

monoclinic

P2₁/c (no. 14)

8

a (Å)

b (Å)

c (Å)

12.017(5)

12.231(5)

12.402(5)

90

1822.9(12)

1.392

11.6841(11)

11.9242(11)

13.9294(11)

90

1940.7(3)

1.355

21.148(10)

7.283(4)

19.986(10)

106.569(13)

2951(2)

2.000

12.552(5)

12.958(5)

19.320(7)

90.167(7)

3142(2)

1.937

23.5390(6)

13.8679(4)

11.7781(3)

109.338(1)

3627.9(2)

2.000

ꢀ (deg)

V (Å³)

F_calcd(g/cm³)

µ_calcd(mm^-1

F(000)

)

1.137

744

1.070

776

1.562

1744

1.470

1808

1.710

2136

θ_max(deg)

total reﬂns measured

28.24

5887

27.49

7749

27.04

26580

25.00

26580

29.95

31036

ind reﬂns [R_int

]

2192 [R_int) 0.077] 2229 [R_int) 0.026]

5690 [R_int) 0.087] 19421 [R_int) 0.149] 5254 [R_int) 0.029]

params reﬁned, restraints

ﬁnal R1 [I > 2σ(I)]/all data^b

ﬁnal wR2 [I > 2σ(I)]/all data

goodness of ﬁt on F²

103, 0

108, 0

415, 128

0.087/0.115

0.202/0.221

1.047

435, 136

0.072/0.151

0.155/0.202

1.003

295, 10

0.047/0.057

0.103/0.107

0.991

0.023/0.025

0.053/0.054

1.059

0.031/0.075

0.043/0.086

1.120

b

c

solvent-accessible volume/cell

654 (35.9%)

666 (34.3%)

0.32 and -0.31

largest diff. peak and hole e·Å^-31.63 and -0.58

0.72 and -0.50

0.88 and -0.96

1.74 and -0.88

^aThe unknown solvent content of compounds 2·solv and 5·solv was SQUEEZED with program PLATON³¹prior to ﬁnal reﬁnement and is not contained

in chemical formulae and quantities derived thereof (F_w, F_calcd, µ_calcd, and F(000)). ^bR1 ) ∑||F₀| - |F_c||/∑|F₀| and wR2 ) {∑[w(F₀²- F_c)] /∑[w(F₀)²]}^1/2

2

^cSolvent-accessible volume/cell: This is the volume (Å³) of open space available to a sphere of radius 1.2 Å for the solvated compounds 2·solv and 5·solv.

Table 2. Selected Bond Distances and Angles for 2·solv and 5·solv

type NH · · ·F and also CH · · ·F bonds involving the aromatic

ring, with the latter type being weaker.^33,35There also exist

Ag · · · F contacts.^9b,33,36The Ag-F distances, 2.95 Å for 2

and 2.92 Å for 5, are shorter than the sum of the van der

Waals radii (3.19 Å).³⁷Moreover, inside the chain there are

short CH · · · Ag contacts^4d,38,39(two per silver atom) with

the ortho CH group of the aryl ring (see Table 4). The

H · · · Ag and N · · · Ag distances also correspond to contacts

between the NH₂groups and the silver centers (see Table

4). These CH · · · Ag and NH₂· · · Ag contacts are present in

all derivatives described in this paper and will not be detailed

below (see Table 4 for the distances and angles)

[Ag(Phdat)(BF₄)]_n·

solv, 2·solv

[Ag(Toldat)(BF₄)]_n·

solv, 5·solv

Ag1-N1

N1-Ag-N1

Ag1-F

N1-C1

N1-C2

N2-C1

N3-C1

C2-C3

C3-C4

C4-C5

C5-C6

C6-C7

2.142(4) (2×)

2.144(2) (2×)

179.5(3)

171.1(1)

2.948(4) [F1] (2×)

1.373(6)

1.361(6)

1.314(6)

1.327(7)

1.429(12)

1.384(7)

1.413(7)

2.923(2) [F1] (2×)

1.365(3)

1.339(2)

1.338(3)

1.316(3)

1.461(6)

1.394(3)

1.385(4)

1.369(4)

1.374(8)

1.513(6)

Complex 3. This complex crystallizes in the monoclinic

space group P2₁/c. A dimeric unit of formula [Ag₂-

(Phdat)₂(CF₃SO₃)₂] with two triﬂate bridges can be consid-

ered as the fundamental building block of this structure (see

Figure 3). In this unit, each silver atom has a tetrahedral

coordination geometry and is bonded to the two triﬂate

bridges that exhibit a κ²O,µ₂-O coordinative fashion and to

one nitrogen atom of a triazine of the unit. Each silver center

The chains are packed parallel to the ab plane to give a

warped sheet of chains linked through the BF₄^-groups (see

Figure 2). These warped sheets are connected through

-

interactions with the BF₄anions along the c axis. In this

way, a sequence of planes ABAB... is obtained, with a mutual

offset of the sheets by a/2 (Figure 2). This feature creates

continuous channels along the b axis, and disordered solvent

is included in these voids (in Figure 2, the solvent molecules

have been removed). The average diameter of the channels

is about 5 Å. Viewed along a {Ag(L)} chain, that is, parallel

to the a axis, each chain is surrounded by six others in an

elongated hexagonal disposition (see Figure S1, Supporting

Information). The interactions that allow the formation of

this network involve contacts between the ﬂuorine atoms of

the anions and different groups on the chains (see Table 4).

Other examples have been described of chains that are linked

through the anions via weak interactions^33,34in silver

compounds. In our case, there are hydrogen bonds⁴of the

(34) (a) Fei, B.-L.; Sun, W.-Y.; Tang, W.-X. J. Chem. Soc., Dalton Trans.

2000, 805–811. (b) Hsu, Y.-F.; Chen, J.-D. Eur. J. Inorg. Chem. 2004,

1488–1493.

(35) (a) Grepioni, F.; Cojazzi, G.; Drapper, S. M.; Scully, N.; Braga, D.

Organometallics 1998, 17, 296–307. (b) Manzano, B. R.; Jalo´n, F. A.;

Ortiz, I. M.; Soriano, M. L.; Go´mez de la Torre, F.; Elguero, J.;

Maestro, M. A.; Mereiter, K.; Claridge, T. D. W. Inorg. Chem. 2008,

47, 413–428.

(36) (a) Zheng, Y.; Li, J.-R.; Du, M.; Zou, R.-Q.; Bu, X.-H. Cryst. Growth

Des. 2005, 5, 215–222. (b) Halper, S. R.; Cohen, S. M. Inorg. Chem.

2005, 44, 486–488. (c) Hu, H.-L.; Yeh, C.-W.; Chen, J.-D. Eur.

J. Inorg. Chem. 2004, 4696–4701.

(37) Bondi, A. J. Phys. Chem. 1964, 68, 441–451.

(38) (a) Brookhart, M.; Green, M. L. H.; Parkin, G. PNAS 2007, 104, 6908–

6914. (b) Crabtree, R. H. Angew. Chem., Int. Ed. 1993, 32, 789–805.

(39) Thakur, T. S.; Desiraju, G. R. Chem. Commun. 2006, 552–554.

(33) Wei, K.-J.; Ni, J.; Gao, J.; Liu, Y.; Liu, Q.-L. Eur. J. Inorg. Chem.

2007, 3868–3880.

8962 Inorganic Chemistry, Vol. 47, No. 19, 2008

Self-Assembly of SilWer(I) and Diaminotriazines

Table 3. Selected Bond Distances (Å) and Angles (deg) for 3, 6, and 7

[Ag(Phdat)(OTf)]_n, 3

[Ag(Toldat)(OTf)]_n, 6

[Ag₃(Phdat)₂(H₂O)(Me₂CO)₂(BF₄)₃]_n, 7

Ag1-N1

2.375(8)

2.298(8)

2.413(11)

2.364(9)

2.327(8)

2.379(8)

2.445(9)

2.423(10)

109.9(3)

116.6(5)

95.9(3)

115.9(5)

133.2(4)

83.2(5)

109.9(3)

127.5(4)

118.0(5)

94.5(3)

Ag1-N1

2.297(8)

2.222(8)

2.558(7)

2.494(7)

2.202(8)

2.225(8)

2.573(7)

2.578(7)

135.2(3)

91.0(3)

Ag1-N1

2.246(2)

2.240(2)

2.439(2)

2.810(2)

2.193(2)

2.716(2)

Ag1-N3

Ag1-N6

Ag1-N3^a

Ag1-O1

Ag1-F7

Ag2-N2

Ag2-O2

Ag1-O2

Ag1-O1

Ag1-O4

Ag2-N6

Ag2-N2

Ag2-N8

Ag2-O1

Ag2-O2

Ag2-O5

Ag2-O4

N1-Ag1-N3

N1-Ag1-O2

N1-Ag1-O4

N3-Ag1-O2

N3-Ag1-O4

O4-Ag1-O2

N6-Ag2-N8

N6-Ag2-O1

N6-Ag2-O5

N8-Ag2-O1

N8-Ag2-O5

O1-Ag2-O5

N1-Ag1-N6

N1-Ag1-O1

N1-Ag1-O4

N6-Ag1-O1

N6-Ag1-O4

O1-Ag1-O4

N2-Ag2-N8

N2-Ag2-O2

N2-Ag2-O4

N8-Ag2-O2

N8-Ag2-O4

O2-Ag2-O4

N1-Ag1-N3^a

N1-Ag1-O1

N3^a-Ag1-O1

O1-Ag1-F1

N1-Ag1-F1

N2^b-Ag2-N2

O2-Ag2-O2

N2-Ag2-O2

132.49(8)

117.68(6)

109.49(6)

85.87(7)

83.75(8)

180.0

81.7(3)

98.6(3)

137.8(3)

100.4(2)

146.5(3)

101.7(3)

104.9(3)

92.4(3)

180.0

81.49(9)

116.9(5)

87.3(4)

97.7(3)

111.6(2)

^ax, -y, z + 1/2. ^b-x + 1/2, -y + 1/2, -z + 1.

Figure 1. The polymeric chain of complex 2 that extends along the a axis: (a) view along the c axis and atom numbering; (b) view along the b axis with

phenyl groups omitted for clarity.

Consequently, each dimeric unit is bonded to another four

units that are rotated by 180° with respect to the former

around the crystallographic b axis (see Figure 4). In this way,

a sheet extending along the ab plane is formed. The

O-Ag-O angles (83-87°) are considerably smaller than

the N-Ag-N angles (109.9°). The nitrogen atoms used to

coordinate to the silver center are, as in the previous

complexes, N¹and N⁵of the triazine rings. The thickness of

the sheets, measured as the distance between the two limiting

and parallel planes passing through the para-H of the phenyl

rings, is 8.93 Å.

It can be clearly seen in Figure 4a that the two rings of a

Figure 2. Complex 2. Ball and stick view of the channels that extend along

speciﬁc triazine ligand are not located in the same plane,

and the corresponding interplanar angles are 45.1° (phenyl-

triazine 1 with N1) or 43.2° (phenyl-triazine 2 with N6). As

in the previous complexes, the silver atoms are not in the

same plane as the triazine rings, the distances between Ag

and these planes being (0.64 and (0.93 Å. In contrast to 2

the b axis formed with three sheets. The {Ag(L)} chains shown in Figure

1 are connected through interactions with the BF₄anions. Pink ) Ag; blue

) N; grey ) C; orange ) B; green ) F; pale blue ) H.

is also bonded to a triazine ring of another unit. The Ag-Ag

distance is 5.68 Å. In addition, one nitrogen atom of each

triazine ring is bonded to silver atoms of other units.

Inorganic Chemistry, Vol. 47, No. 19, 2008 8963

Manzano et al.

Table 4. Distances (Å) and Angles (deg) for Noncovalent Interactions in Complexes 2, 3, 5, 6, and 7

hydrogen bonds in the ligands

NH· · ·F

N3-(H)· · ·F

CH· · ·F

C4-(H)· · ·F1

3.28(1)

CH· · ·Ag

C-(H)· · ·Ag

NH · · ·Ag

compd

NHF

CHF

140

Ag1 · · ·F1

CHAg

96

N-(H)· · ·Ag

NHAg

114

2

2.96(1) [F1]

3.00(1) [F1]

2.96(2) [F2]

2.97(2) [F3]

3.081(3) [F1]

3.196(4) [F2]

3.05(2) [F3]

3.18(2) [F3]

119

146

166

171

148

138

154

148

2.948(4) (2×)

3.181(6) [C4,Ag1]

3.246(5) [N3,Ag1]

5

3.319(3)

137

2.923(2) (2×)

3.099(2) [C4,Ag1]

95

3.281(2) [N3,Ag1]

114

NH· · ·O (intra^a)

N-(H)· · ·O

NH· · ·O (inter^b)

N-(H)· · ·O

CH· · ·Ag

NH · · ·Ag

NHO

C-(H)· · ·Ag

CHAg

N-(H)· · ·Ag

NHAg

3

6

2.99(2) [N4,O4]

3.10(2) [N5,O3]

2.93(2) [N9,O6]

3.01(2) [N10,O1]

3.10(1) [N4,O1]

3.24(1) [N4,O4]

3.14(1) [N5,O2]

3.01(1) [N9,O1]

3.04(1) [N10,O2]

2.88(1) [N10,O5]

166

131

136

152

164

174

168

165

167

159

3.00(2) [N4,O3]

3.00(1) [N5,N2]

3.02(1) [N9,N7]

3.36(2) [N10,O6]

2.90(1) [N5,N7]

2.99(1) [N9,N3]

158

159

157

142

158

159

2.94(1) [C5,Ag1]

3.06(1) [C9,Ag1]

2.94(1) [C14,Ag2]

3.11(1) [C18,Ag2]

3.36(1) [C5,Ag1]

3.14(1) [C15,Ag2]

96

90

91

93

91

88

3.55(1) [N4,Ag1]

3.54(1) [N5,Ag1]

3.51(1) [N9,Ag2]

3.62(1) [N10,Ag2]

3.18(1) [N9,Ag1]

3.13(1) [N5,Ag2]

120

113

116

115

118

117

NH· · ·F (intra^a)

2.874(6) [N4,F5]

AH· · ·B (inter^b)

C-(H)· · ·Ag

CHAg

N-(H)· · ·Ag

NHAg

7

130

2.728(3) [O1,F4]

2.993(4) [N5,O2]

3.125(4) [N5,F1]

3.061(5) [N5,F3]

3.041(2) [N4,F4]

3.199(7) [N4,F6]

3.435(3) [N4,F7]

143

3.193(3) [C5,Ag1]

3.011(3) [C9,Ag2]

91

95

3.359(3) [N4,Ag1]

3.268(3) [N4,Ag1]

3.302(2) [N5,Ag2]

110

117

146

138

155

166

124

177

^aIntra refers to intralayer in the case of 3 and to intraladder in the cases of 6 and 7. ^bInter refers to interlayer in the case of 3 and to intraladder in the

cases of 6 and 7.

Figure 3. Structural diagram of compound 3 including intralayer hydrogen bonds.

and 5, the triazine rings are practically planar in complex 3

(aplanarity < 0.02 Å).

17.5-25.9°. There are also intralayer N-H · · · O hydrogen

bonds between NH₂and the triﬂate groups (see Table 4 and

Figure 3). These bonds involve the two amino hydrogens

that are oriented toward the inside of the sheet and free as

well as Ag-coordinated oxygen atoms of the counteranion.

As can be seen from Figure 5, the asymmetric unit has an

arrangement of four ADAD centers constituted by the

uncoordinated oxygen atom of a triﬂate, an amino group,

the triazine N³atom, and the second amino group. In the

adjacent sheet, there exist the complementary DADA groups

related by inversion, and in this way, sets of four hydrogen

bonds are formed that connect the 2D networks perpendicular

to (001) to form a three-dimensional superstructure (see Table

4 for the hydrogen-bonding distances).

As shown in Figures 3 and 4, in the structure there is a

noticeable motive for assembly between the elemental

building blockssnamely, triazine-phenyl π-π stacking.⁵

The respective electron-poor and electron-rich character of

these aromatic rings reinforces the bonding in the lamellar

structure. This stacking extends along the crystallographic

b axis and leads to the formation of columns of alternating

electron-poor and electron-rich aromatic rings (the columns

are indicated by arrows in Figure 4c). Columnar stacking

between aromatics and triazine rings has also been described

by Fujita et al.^15c,dThe intercentroid ring distances display

alternate values of 3.78 and 3.52 Å and the centroid-plane

distances are in the range 3.36-3.40 Å, with an angle

between planes of 3.3-3.8° and a slipping angle of

Complex 6. This complex crystallizes in the space group

P2₁/n. It is remarkable that 6 differs from 5 only in an

8964 Inorganic Chemistry, Vol. 47, No. 19, 2008

Self-Assembly of SilWer(I) and Diaminotriazines

Figure 4. (a) Schematic view of the building unit of 3. (b) Schematic representation of the unit. A continuous or a dotted line represents a triﬂate bridge

that is in front of or behind the projection plane. A blue rectangle represents the triazine ring and a green rectangle the phenyl ring. (c) 2D network of one

sheet. The arrows represent the columns in which π-π stacking is present.

Figure 5. Crystal structure of 3 with unit cell viewed along the b axis.

Intra- and interlayer NH · · ·N and NH · · ·O hydrogen bonds are marked as

dotted lines.

Figure 6. (a) Ladderlike polymer of complex 6 that extends along the a

axis. (b) The same for complex 7 along the c axis. The H atoms and those

atoms of the bridging groups that do not participate in the bridge have been

omitted for clarity.

additional methyl group, but the structure is completely

different. The structure can be considered as consisting of

ladderlike polymers that extend along the a axis and are

mutually connected through hydrogen bonds to build a 3D

supramolecular architecture. The ladders have several special

characteristics that make them very unusual (see Figures 6a

and 7). In principle, this structure may be compared with

the same oxygen atom is bonded to the two silver centers

(κ¹O,µ₂-O). The four silver atoms deﬁne a parallelogram,

and the sides of the ladder are occupied by triazine ligands

situated in parallel planes and bonded this time through the

N¹and N³atoms and with a head-to-tail disposition.

However, in contrast to the situation usually found in ladder

structures, the two ligands are not eclipsed but are clearly

displaced. In the middle of the resulting Ag₄unit, there is

an inversion center. This parallelogram is fused with another

one in which the triazine ligands have a different orientation.

The dihedral angle formed by two consecutive triazine rings

is 70.3°. In this way, the fused Ag₄units alternate the

orientation of the triazines along the polymer. As in the

previous complexes, the triazine and aryl (tolyl) rings are

not coplanar (dihedral angles between 37 and 42°). Likewise,

the silver centers are not in the triazine planes showing

40

the structure of NbOCl₃in the sense that the rungs are

constituted by a double bridge. In both structures, the nodes

are the metallic centers, and in the niobium derivative, the

bridges are the chlorine atoms, whereas in complex 6, the

two triﬂate groups form an asymmetric bridge. In fact, one

triﬂate is coordinated in a κ²O,µ₂-O fashion, and in the other,

(40) (a) Sands, D. E.; Zalkin, A.; Elson, R. E. Acta Crystallogr. 1959, 12,

21–23. (b) Stro¨bele, M.; Meyer, H.-J. Z. Anorg. Allg. Chem. 2002,

628, 488–491.

Inorganic Chemistry, Vol. 47, No. 19, 2008 8965

Manzano et al.

Although other examples of double-bridged rungs are

known,⁴²it is not common for these to be asymmetric in

nature. Even though a silver ladder structure in which

octagons and rhombuses alternate along the chain have been

described,⁴³in our case, the offset disposition of the sides

and the alternating orientation of ligands in these sides are

extremely uncommon. These two facts give to the polymer

a more three-dimensional nature, and this could also be

considered as a tubular chain.

Complex 7. This compound crystallizes in the monoclinic

space group C2/c. Its composition may be given as

Ag₂(Phdat)₂(H₂O)(BF₄)₂· Ag((CH₃)₂CO)₂(BF₄). The com-

pound is built up from a Ag1 ion in triangular planar

coordination by two triazine nitrogen atoms and the oxygen

atom of a water molecule (Figure 9). The triangular-planar

coordination of Ag1 is supplemented by two F atoms from

two inequivalent BF₄tetrahedra to form a very distorted

trigonal bipyramidal coordination ﬁgure Ag(N₂OF₂). The

Ag-F distances are shorter than the sum of the van der

Waals radii (Table 3), and cases have been described of

interactions or bonds with similar values.⁴⁴The second Ag

atom of the compound, Ag2, is in a special position with

point symmetry C_iand has a square-planar coordination by

two triazine nitrogen atoms N⁵and two weakly bonded

oxygen atoms⁴⁵of acetone molecules. The Phdat ligand is

in a general position and consists of two essentially ﬂat six

rings (rms aplanarities of 0.035 Å for the triazine ring and

of 0.018 Å for the phenyl ring) with a dihedral ring-ring

inclination of 47.8(9)°. It is bonded to two Ag1 via N¹and

N³and to one Ag2 via N⁵. The silver centers are outside the

triazine plane (distances of (0.874(1) Å for Ag1 and

(0.4700(2) for Ag2). There are two independent BF₄

tetrahedra, of which that of B1 is in a general position and

terminally bonded to Ag1, whereas that of B2 together with

its F7 atom (weakly bonded to two Ag1) is located on a

2-fold axis, which implies that the remaining three F atoms

of B2 are disordered, being distributed over three half-

occupied positions, F5, F7, and F8. The water molecule H₂O1

is located on a 2-fold axis and bridges two Ag1’s (Ag-O-Ag

) 110.7(7)°). The acetone molecule as the last constituent

is in general position and terminally bonded to one Ag2 with

an angle C32dO2-Ag2 ) 147°.

Figure 7. Complex 6. Two fused units showing the intramolecular (in

green) and the intermolecular (in red) hydrogen bonds. H atoms and CF₃

groups omitted for clarity. Yellow ) S.

comparatively large deviations (distances to triazine planes

vary from 0.71 to 1.48 Å). The two independent silver atoms

exhibit distorted tetrahedral coordination geometries (see

Table 4 for the distances and angles). Like in 3, the

O-Ag-O angles are smaller than the N-Ag-N angles, with

both of these angles larger than those found in the phenyl

derivative. In fact, one N-Ag-N angle has a value of

146.4°.

Each Ag₄unit has four amino groups, that is, eight

hydrogen donors to form hydrogen bonds, and as acceptors,

there are the oxygen atoms of the triﬂate anions and triazine

N⁵atoms. Inside this parallelogram, six hydrogen bonds are

formed involving the triﬂate groups (see Figure 7). Interest-

ingly, one hydrogen donor and the N⁵atom of each ligand

are oriented outside the unit and form a double hydrogen

bond with another chain. In this way, the chain is hydrogen-

bonded to two neighboring chains in the [011] direction. The

subsequent unit within the chain, displaced relative to the

preceding by a/2, has the same hydrogen-bonding system

but adopts a (010) mirror related orientation. Therefore, it

j

links with two neighboring chains in the [011] direction. As

a result, a 3D supramolecular structure is formed (Figure

8a). The existence of this hydrogen-bonded net means that

all of the hydrogen-bond donors and acceptors of the triazine

ring are used in the formation of hydrogen bonds. The tolyl

groups are situated outside the chains and deﬁne hydrophobic

regions that are parallel to the ab plane. The OTf groups are

oriented with their CF₃groups tail-to-tail with mutual F · · ·F

contacts approximately parallel to the b axis.⁴¹The F · · · F

contact distances are about 2.9 Å and should be considered

as virtual because both CF₃groups apparently suffer from

orientation disorder, as indicated by their large anisotropic

displacement parameters.

The Ag1 atoms and the triazine ligands deﬁne a ladderlike

polymer constituted by fused Ag₄units (extended along the

(42) (a) Hou, H.; Xie, L.; Li, G.; Ge, T.; Fan, Y.; Zhu, Y. New. J. Chem.

2004, 28, 191–199. (b) Zhang, G.; Yang, G.; Shi, M. J. Cryst. Growth

Des. 2006, 6, 1897–1902.

(43) Zhong, J. C.; Munakata, M.; Maekawa, M.; Kuroda-Sowa, T.; Suenaga,

Y.; Konaka, H. Inorg. Chim. Acta 2003, 342, 202–208.

(44) (a) Camalli, M.; Caruso, F. Inorg. Chim. Acta 1987, 127, 209–213.

(b) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Sironi, A. J. Am. Chem.

Soc. 1995, 117, 4562–4569. (c) Bertelli, M.; Carlucci, L.; Ciani, G.;

Proserpio, D. M.; Sironi, A. J. Mater. Chem. 1997, 7, 1271–1276. (d)

Haftbaradaran, F.; Draper, N. D.; Leznoff, D. B.; Williams, V. E.

Dalton Trans. 2003, 2105–2106.

(45) (a) Edema, J. J. H.; Stock, H. T.; Buter, J.; Kellogg, R. M.; Smeets,

W. J. J.; Spek, A. L.; Bolhuis, F. Angew. Chem., Int. Ed. Engl. 1993,

32, 436–439. (b) Bowmaker, G. A.; Effendy; Marfuah, S.; Skelton,

B. W.; White, A. H. Inorg. Chim. Acta 2005, 358, 4371–4388. (c)

Powell, J.; Horvath, M. J.; Lough, A.; Phillips, A.; Brunet, J. Dalton

Trans 1998, 637–645. (d) Doppelt, P.; Baum, T. H.; Ricard, L. Inorg.

Chem. 1996, 35, 1286–1291. (e) Chen, X.-D.; Mak, T. W. J. Mol.

Struct. 2005, 748, 183–188.

As stated above, the structure of complex 6 can be

considered as a very unusual type of ladderlike structure.

(41) (a) Vangala, V. R.; Nangia, A.; Lynch, V. M. Chem. Commun. 2002,

1304–1305. (b) Metrangolo, P.; Neukirch, H.; Pilati, T.; Resnati, G.

Acc. Chem. Res. 2005, 38, 386–395.

8966 Inorganic Chemistry, Vol. 47, No. 19, 2008

Self-Assembly of SilWer(I) and Diaminotriazines

Figure 8. (a) View down the a axis of ﬁve chains connected through pairs of hydrogen bonds for complex 6. (b) View down the c axis of ﬁve chains (in

black) connected through “Ag(acetone)₂” fragments (in red) for complex 7. H atoms omitted for clarity.

18 and 21°. In this complex, there are also short distances

between F atoms of the B(2)F₄^-group and the triazine ring

(F-plane distances of 2.9-3.2 Å) that are indicative of

anion-π interaction. This type of interaction is receiving

increasing attention, and it has been found involving triazine

rings.^35b,46

In this compound, intraladder hydrogen bonds involving

-

NH₂groups and the BF₄situated inside the ladder are

observed. Outside the ladder, there are also these kinds of

-

bonds with the participation of NH₂and BF₄groups and

also the oxygen atoms of water and acetone molecules.

One unit of the ladder is connected to the other two ladders

to form a sheet [along the plane (220)], and the following

unit is also connected in the same way but to form a sheet

j

in the plane (220). In this way, the 3D dimensional structure

is formed. This is completely similar to that found in 6, but

perhaps the most intriguing thing is that the role played by

the hydrogen bonds in 6 to build the superstructure is played

here by [Ag(acetone)₂] units that are bonded to two triazine

ligands from two different chains (see Figure 8b). In this

way, complex 7 can be considered as a MOF derivative. It

is observed that the methyl groups of the acetone ligands

are oriented toward the same region of the space (hydro-

phobic effect), and the BF₄^-groups occupy holes formed in

the structure.

Figure 9. Two fused units of complex 7. The silver centers of the ladder

are in pink. The silver atoms in green or yellow form the sheets on different

planes (see text). Only the hydrogen bonds inside the ladder are indicated

(green). In red are the π-π interactions.

c axis) very similar to that of 6. The nodes are the silver

centers, and the rungs are also constituted by a double and

asymmetric bridge. In this case, instead of the triﬂate anions,

it consists of the water molecule and the B(2)F₄^-group. The

triazine ligands form the sides of the ladder, and they are

situated in a very similar way to that of 6. As in 6, in complex

7, the fused Ag₄units also alternate the orientation of the

triazines along the polymer (see Figure 6b and compare with

Figure 6a). The dihedral angle formed by two consecutive

triazine rings is 53.2°.

A differentiated fact found in 7 that was not observed in

6 is the existence of π-π stacking between triazine and

phenyl rings of consecutive Ag₄units (see Figure 9, red

lines). The angle formed between the two planes is 5.3°;

the centroid-centroid distance is 3.65 Å; the centroid-plane

distances are 3.47 and 3.40 Å, and the slipping angles are

From the topological point of view and considering that

the bridges and the [Ag(acetone)₂] fragments are not nodes,

the three-dimensional framework of 7 is a (3,3)-connected

net, comprised of silver centers and ligands with the Scha¨ﬂi

(46) (a) Mascal, M.; Armstrong, A.; Bartberger, M. D. J. Am. Chem. Soc.

2002, 124, 6274–6276. (b) Demeshko, S.; Dechert, S.; Meyer, F. J. Am.

Chem. Soc. 2004, 126, 4508–4509. (c) Frontera, A.; Saczewski, F.;

Gdaniec, M.; Dziemidowicz-Borys, E.; Kurland, A.; Deya`, P. M.;

Quin˜onero, D.; Garau, C. Chem.sEur. J. 2005, 11, 6560–6567, and

references therein. (d) Schottel, B. L.; Chifotides, H. T.; Shatruck,

M.; Chouai, A.; Pe´rez, L. M.; Bacsa, J.; Dunbar, K. R. J. Am. Chem.

Soc. 2006, 128, 5895–5912. (e) Schottel, B. L.; Chifotides, H. T.;

Dunbar, K. R. Chem. Soc. ReV. 2008, 37, 68–83.

Inorganic Chemistry, Vol. 47, No. 19, 2008 8967

Manzano et al.

coordinated to the silver centers. In derivatives 2, 3, and 5,

it is N³, while for complex 6, it is N⁵. When comparing these

four complexes, it is deduced that the type of anion present

has a dramatic inﬂuence on the silver coordination number

and also on the ﬁnal supramolecule formed. This effect seems

to be mainly related to the coordinating ability of the anion.

Several examples of anion control in silver coordination

polymers have been described.^1fIn some cases, a difference

in the anion coordinating behavior is observed^26,36c,48-50

although in others the differences are due to other fac-

tors,^8,27,33,51including, for example, their size⁵¹or their

shape.^4cIn our case, the coordination of the oxygen atoms

of the triﬂate group induces the formation of double triﬂate

bridges. On the other hand, the type of aryl group present

on the triazine ligand may have an inﬂuence on the network

topology. Complexes 2 and 5, both of which contain the BF₄

anion, have identical structures. It seems that the methyl

groups of the tolyl rings are oriented toward regions of space

whose occupation does not have signiﬁcant consequences

on the ﬁnal architecture. The difference between a phenyl

and a tolyl group is small but sometimes gives rise to very

important changes in behavior.^19bIn fact, in the triﬂate

complexes, the presence of the methyl group on the aryl ring

leads to a dramatic change in the structure. In the phenyl

derivative, sheets exhibiting columns with π-π stacking and

connected through hydrogen bonds are formed, but the tolyl

complex gives rise to a tubular chain in which the stacking

is not observed, but the system adopts a disposition where

an extensive net of hydrogen bonds is established. In fact, a

common feature of the two derivatives is the presence of a

large number of hydrogen bonds involving the triazine and

triﬂate groups in such a way that all of the hydrogen donor

or acceptor groups from the triazine ring are involved. Some

of these bonds are internal, but others are intermolecular and

increase the dimensionality of the derivatives from 2D to

3D (3) or 1D to 3D (6). It can be stated that, for the OTf

complexes, the double hydrogen bond N-H· · ·N/N · · ·H-N

present in the free triazine ligands is maintained (ampliﬁed

to a quadruple bond in the case of 3). This hydrogen bond

is completely broken in the BF₄derivatives 2 and 5, and

weaker noncovalent interactions involving the counteranion

are present, thus increasing the dimensionality from 1D to

3D. All of theses structures show that, besides the covalent

bonds between the silver centers and the ligands, the

architecture is largely inﬂuenced by the noncovalent interac-

tions.

Figure 10. Topological representation of 7. (a) Partial view to emphasize

the nodes in the cycles. (b) View down the a axis. Blue and pink circles

represent the ligands and silver centers of the ladders, respectively. The

small black circles represent the [Ag(acetone)₂] fragments that connect the

ladders.

symbol of (6².10)(6.10²).⁴⁷In Figure 10, two schematic

representations of the network where the ladders run

horizontally are gathered. Figure 10a represents a section of

the framework, and it is intended to reﬂect the number of

nodes in the cycles.

Comparative Analysis of the Structures of 2, 3, 5, 6,

and 7. On comparing the self-assembled supramolecular

architectures of the new compounds, several facts can be

clearly established. In all cases, the silver center is not in

the same plane as the coordinating triazine ring (distances

up to (1.48 Å), and the triazine rings are not coplanar with

the phenyl or tolyl groups (dihedral angles in the range of

37-48°). The latter situation is in contrast to that found in

the free ligand Phdat¹⁷where the interplanar angles for the

two independent molecules are 6.0 and 9.3° (the X-ray

structure of Toldat has not been described). In this sense,

we can state that coordination to the silver center disturbs

the conformation of the triazine ligands, at least in the case

of Phdat. In all derivatives, weak NH · · · Ag and CH · · · Ag

interactions have been detected. In the derivatives with a

Ag/L ratio of 1, one nitrogen atom of the triazine ring is not

Perhaps the most striking fact comes from the comparison

of the structures of compounds 6 and 7. Although they differ

(48) Seward, C.; Chan, J.; Song, D.; Wang, S. Inorg. Chem. 2003, 42,

1112–1120.

(49) Wu, H.-P.; Janiak, C.; Rheinwald, G.; Lang, H. J. Chem. Soc., Dalton

Trans. 1999, 183–190.

(50) (a) Withersby, M. A.; Blake, A. J.; Champness, N. R.; Hubberstey,

P.; Li, W.-S.; Schro¨der, M. Angew. Chem., Int. Ed. 1997, 36, 2327–

2329. (b) Hu, H.-L.; Yeh, C.-W.; Chen, J.-D. Eur. J. Inorg. Chem.

2004, 4696–4701. (c) Chi, Y.-N.; Huang, K.-L.; Cui, F.-Y.; Xu, Y.-

Q.; Hu, C. W. Inorg. Chem. 2006, 45, 10605–10612.

(51) Long, D.-L.; Hill, R. J.; Blake, A. J.; Champness, N. R.; Hubberstey,

P.; Wilson, C.; Schro¨der, M. Chem.sEur. J. 2005, 11, 1384–1391.

(a) Kim, H.-J.; Zin, W.-C.; Lee, M. J. Am. Chem. Soc. 2004, 126,

7009–7014.

(47) (a) Wells, A. F. Further Studies of Three-Dimensional Nets, 1st ed.;

American Crystallographic Association Press: Buffalo, NY, 1979;

Monograph Number 8. (b) Bucknum, M. J. CPS:physchem/0202007,

2002, 1-25. (c) Bucknum, M. J. CPS: physchem/0202006, 2002,

1-40. (d) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Rizzato, S. J.

Solid State Chem. 2000, 152, 211–220.

8968 Inorganic Chemistry, Vol. 47, No. 19, 2008

Self-Assembly of SilWer(I) and Diaminotriazines

in the stoichiometry, counteranions, and triazine substituents,

their structures show an amazing degree of resemblance.

They exhibit extremely similar ladderlike structures. It is also

very noteworthy that the connection between these chains

to form a 3D structure that consists of similar crossed sheets

is effected in complex 6 by hydrogen bonds and in 7 by

silver centers. That is to say, the silver center and the double

hydrogen bond interchange their roles. As for differences,

in 7 there exist triazine-phenyl π-π stacking and anion-π

(triazine-BF₄) interactions.

endothermic peak with several maxima between 300 and 350

°C appears, reﬂecting the decomposition of the material (a

black solid is obtained). It is interesting to note that in

complex 7 where the channels are not present the exothermic

peak found in 2 does not appear.

NMR Characterization in Solution. It is well-known that

silver complexes with nitrogenated ligands exhibit in solution

a dynamic behavior involving interconversion between

different species.^10,13,27,48When low-temperature NMR

spectra are recorded, although changes in chemical shifts are

observed, the interconversion process is not usually slowed

down enough to detect speciﬁc species.^27,48A case has been

described of a silver complex where a ring-spinning process

is frozen out at low temperatures in solution due to a CH · · ·π

interaction.⁵²We were interested in studying the behavior

of our derivatives in solution, and room-temperature and low-

temperature NMR spectra were recorded. Fortunately, we

were able to detect a new species in solution.

Powder X-Ray Diffraction and Thermal Analysis. For

compounds 2, 3, and 6, it was veriﬁed by powder X-ray

diffraction that the monocrystals were representative of the

bulk material (it was supposed that 5 was similar to 2). For

7, the repeated formation of the same derivative was veriﬁed

because the same structure was obtained from three mono-

crystals from three different preparations (only the third

monocrystal was good enough to get data of quality).

A TGA and DTA analysis was performed for 2 and 7. In

the case of 2, the presence of THF, acetone, and water was

1

In the room-temperature H NMR spectra of all deriva-

tives, the R groups in the 6 position of the triazine ring appear

to be symmetric. A single broad resonance assigned to the

NH₂groups is also observed. With the exception of the ortho

protons of the aromatic rings, deshielding of the signals is

observed with respect to the free ligands, a fact due to the

donation of electron density to the metal center. The shift is

clearly higher for the amine resonances (∆δ ) 0.4-1.0). In

the corresponding ¹⁹F NMR spectra, the counteranion

resonances are sharp signals. The ¹³C {¹H} NMR spectra

were only recorded for the more soluble derivatives (see the

Experimental Section) and also reﬂect the presence of

symmetric ligands. Although these facts may also be due to

the presence of highly symmetric species, we propose that

an exchange process exists in solution.

The ¹H NMR spectra of all complexes at low temperatures

(-80 °C, acetone-d₆) were also recorded. As in the free

triazines, the broad resonance assigned to the NH₂groups is

split into two signals at -80 °C. This indicates a more

restricted rotation of the triazine-NH₂bond at low temper-

atures. In addition, the chemical shift (averaged) of these

resonances increases. Both of these facts could be related to

the existence of DA/AD hydrogen-bond pairs between pairs

of ligands in solution. As far as the resonances of the R group

of the triazine ring are concerned, a slight broadening of some

signals is observed in all cases. For instance, a broadening

of the ortho resonance of complex 1 was observed at low

temperatures. These observations indicate that the dynamic

processes are also operating at -80 °C in acetone.

1

detected from H NMR spectra. When a freshly prepared

sample was heated (Figure S2, Supporting Information), an

initial mass loss of 8.3% was detected up to ca. 155 °C.

Within it, a change in the slope was observed, and two mass

variations of approximately 3.6 and 4.6% can be considered.

The ﬁrst could correspond to the loss of acetone and THF

and the second to a mole of H₂O per mole of complex. At

the same time, an endothermic peak appeared centered at

156 °C. When the sample was not freshly prepared (Figure

S3, Supporting Information), this initial loss was 3.7%,

indicating a previous and partial loss of solvents on storage.

In both samples, an exothermic peak was also observed at

196 °C, while the weight remained constant. At ap-

proximately 260 °C, it started a second mass loss, and an

endothermic peak was also observed with two maxima at

319 and 330 °C. When the sample was recovered, it was a

spongy black material, a fact that reﬂects the decomposition

of the product. In order to get further information about the

exothermic peak, two samples of 2 were heated in the ATD-

TG apparatus, one up to 170 °C (2-170) and the other up to

220 °C (2-220), and a powder diffractogram was recorded

for both. The sample 2-170 is amorphous (Figure S4,

Supporting Information), while 2-220 is crystalline (Figure

S5, Supporting Information) with a pattern different from

that of the nonheated sample. Consequently, the loss of the

solvents of the channels leads initially to an amorphous

sample which, on heating, is transformed into a crystalline

structure probably more compact than the initial one, and

the peak observed at 196 °C corresponds to this transforma-

tion.

The distinct behavior of complexes 2 and 3 is noticeable.

Besides the splitting of the NH₂resonances and the presence

of several signals similar to those found at room temperature,

a set of ﬁve new resonances (one overlapped) of equal

intensity are observed at -80 °C (see Figure 11). The studies

described below were carried out on complex 2 because the

In the case of 7, a very slow mass reduction of 3.5% up

to approximately 280 °C accompanied by a weak endother-

mic peak was observed (Figure S6, Supporting Information).

This must correspond to the loss of acetone and water. The

value of 3.5% (smaller than the mass percentage of these

solvents in the formulas, 12.3%) indicates that the solvents

have been partially lost at room temperature. At ca. 280 °C,

a sharp mass variation starts, and at the same time, an

1

resonances at low temperatures were sharper. A H-¹H

correlation spectroscopy spectrum demonstrated that the new

signals are coupled and belong to a single phenyl group (one

(52) Childs, L. J.; Pascu, M.; Clarke, A. J.; Alcock, N. W.; Hannon, M. J.

Chem.sEur. J. 2004, 10, 4291–4300.

Inorganic Chemistry, Vol. 47, No. 19, 2008 8969

Manzano et al.

Figure 11. Variable-temperature ¹H NMR spectra of 2 in an acetone-d₆solution. The resonances assigned to the new derivative are indicated. The spectrum

inside the rectangle corresponds to a solution with a Phdat/AgBF₄ratio of 1:2 at -80 °C.

meta resonance is overlapped with other resonances). These

data indicate that we have detected at low temperatures a

deﬁned species that contains an asymmetric aryl group. The

spectra recorded at different temperatures are gathered in

Figure 11, and it is possible to see that at -70 °C (even at

-60 °C) the new species is already present, albeit at a lower

concentration. Consequently, the ratio of the new product

increases as the temperature is lowered. The most striking

feature of these signals is that one ortho proton appears to

be highly shielded (5.43 ppm). In order to obtain more

information about the structure of the new compound, a series

of NMR experiments with derivative 2 were recorded. Given

its low solubility (reduced at low temperature), it was not

possible to record the ¹³C or ¹³C{¹H} NMR spectra of 2,

although we were able to determine the chemical shift of

the phenylic CH resonances at -80 °C with the aid of a

g-HMQC experiment. The carbon bonded to the shielded

proton appears at 124.2 ppm, a reasonable value for a

phenylic carbon. Changes were not observed in the ¹⁹F NMR

Although other options such as a η²interaction or π-π

stacking cannot be conclusively discarded, they are consid-

ered less probable for the following reasons. A η²interaction

of the C_ipso-C_orthobond with the silver center should be

associated with more marked changes in the chemical shift

of the C_orthoatom. The existence of π-π stacking of the

aromatic rings should, in principle, also lead to changes in

the chemical shifts of the meta protons and affect in a more

similar way the two ortho protons, contrary to the results

found in our complex.

Although it is not possible to propose a speciﬁc structure

for this derivative detected at low temperatures, one pos-

sibility is an oligomeric form of complex 7. In any case, the

formation of derivatives with a Ag/L ratio higher than 1 is

demonstrated with complex 7. The extra silver centers could

be coordinated to the third nitrogen atom of the triazine ring,

to acetone molecules, or to the tetraﬂuoroborate counteranion

as it is observed in complex 7.

1

spectrum at -80 °C. The H NMR spectra at -80 °C of

Conclusions

mixtures Phdat/AgBF₄in 1:2 and 2:1 ratios were also

recorded. In the ﬁrst case, the amount of the new species

increased signiﬁcantly (see spectrum inside the rectangle in

Figure 11), while it was reduced for a 2:1 ratio. These results

could imply a Ag/L ratio higher than 1 for the new derivative.

It is also worth noting that for the shielded proton the

coupling constant J_HH(6.4 Hz) is lower than the J_HHfor

the other ortho proton (7.7 Hz) and also lower than that

expected for a phenyl ring.

These facts (chemical shift, reduced J_HH) can be explained

with the following: (i) the existence of an agostic interaction

between silver(I) and the C_Ar-H bond s however, these

interactions are considered not probable for electron-rich

metals^4d,38,39,53s and (ii) the existence of a C-H · · · Ag

hydrogen bond.^4d,38a,39,53In this case, the shielding of the

ortho proton could be due to the anisotropy of an aromatic

ring through, for example, a C-H · · · π interaction.

We have demonstrated that the self-assembly of the Ag(I)

cation and 2,4-diamino-6-R-1,3,5-triazines (R ) phenyl or

p-tolyl) can give rise to a range of three-dimensional and

diverse networks whose precise architecture is R and anion-

dependent and where noncovalent interactions play an

important role. Hydrogen bonds have been found with the

participation in some cases of the triﬂate oxygen atoms, π-π

stacking, anion-π interactions and Ag · · · F, CH · · ·Ag, or

NH · · ·Ag contacts. Different combinations of these second-

ary interactions have been found in the distinct type of

supramolecules obtained. The π-π stacking interaction has

only been observed in the phenyl derivatives. Some of these

supramolecular interactions lead to an increase in the

dimensionality from 1D to 3D or from 2D to 3D networks.

3

-

When the anion is BF₄, with both types of R groups,

chiral helical chains with linear silver centers are formed

that are interlinked through the anions by secondary interac-

tions to give a 3D structure. The OTf^-counteranion

coordinates to the silver atom, which becomes tetracoordi-

(53) Liu, C.-S.; Chen, P.-Q.; Tian, J.-L.; Bu, X.-H.; Li, Z.-M.; Sun, H.-

W.; Lin, Z. Inorg. Chem. 2006, 45, 5812–5821.

8970 Inorganic Chemistry, Vol. 47, No. 19, 2008

Self-Assembly of SilWer(I) and Diaminotriazines

nated. In this case, a strong inﬂuence of the R group is

observed, and a laminar structure or an unusual type of ladder

chain is formed. In the triﬂate derivatives, all of the hydrogen

donor or acceptor groups from the triazine ring are involved

in hydrogen bonds, and the double N-H · · · N/N · · · H-N

system found in the free ligands is maintained (ampliﬁed to

a quadruple bond in the case of the phenyl derivative). A

MOF derivative has also been isolated of formula

[Ag₃(Phdat)₂(OH₂)(acetone)₂(BF₄)₃]_nwhose structure is strik-

ingly similar to that of the complex [Ag(Toldat)(OTf)]_n,

although the complexes differ in stoichiometry, the anion,

and the triazine substituent. The role played by the hydrogen

bonding in the latter to build the 3D structure is played by

silver centers in the former. In the phenyl derivatives with

the BF₄^-or OTf^-anions, a species has been detected at low

temperatures that contains an asymmetric phenyl group.

The effect of other counteranions and that of the solvent

are under study at this moment.

Further studies are clearly needed in order to evaluate the

inﬂuence of all factors on the outcome of supramolecular

architectures if we hope to understand the self-assembly

process and to progress in the ﬁeld of crystal engineering.

Acknowledgment. This work was supported by the DGES

of the Ministerio de Educacio´n y Ciencia of Spain (CTQ2008-

03783/BQU) and the Junta de Comunidades de CastillasLa

ManchasFEDER Funds (PCI08-0054-8714). The authors

acknowledge Dr. Juan Pedro Andre´s and Carlos Rivera from

the UCLM for the recording of the X-ray powder diffrac-

tograms and thermal analysis.

Supporting Information Available: X-ray crystallographic ﬁles

(CIF) for 2, 3, 5, 6, and 7. Graphics of the TGA and DTA thermal

analysis of 2 and 7. This material is available free of charge via

the Internet at http://pubs.acs.org.

IC800997D

Inorganic Chemistry, Vol. 47, No. 19, 2008 8971

Article Doi

Anion-dependent self-assembly of silver(I) and diaminotriazines to coordination polymers: Non-covalent bonds and role interchange between silver and hydrogen bonds

DOI: 10.1021/ic800997d

Source and publish data:

Authors:

Article abstract of DOI:10.1021/ic800997d

Full text of DOI:10.1021/ic800997d

Products guided by the article

R&D Labs maybe for 1061683-98-4

Relevant to this article

Hot Product