Crystal engineering of mixed-metal Ru-Ag coordination networks by using the trans-[RuCl2(pyz)4] (pyz = pyrazine) building block.

In the rational development of new strategies for the crystal engineering of coordination networks[1] and of metal-based supramolecular architectures[2] the use of predetermined building blocks has assumed an increasing relevance in recent times. For example, molecular corners containing transition metals with programmed coordination angles, such as cisprotected PdII and PtII square-planar complexes, have been employed for the construction of frameworks and, particularly, of macromolecular polygons or polyhedral cages,[3] of potential utility for molecular recognition. We have recently employed the corner unit [Cu(2,2 -bpy)]2 (2,2 -bpy 2,2 bipyridine) for the self-assembly of polymeric species[4] and new architectures.[5] These building blocks generally work as acceptors and can be used with a variety of spacer ligands with different types of donor ends for the assembly of desired arrays. A different type of potentially useful metal-containing unit is represented by complexes containing ligands with exooriented donor functions. These complexes can be considered as nonconventional TMligands∫ in which the orientation of the donor groups can be controlled by the nature of the coordinated bases and by the coordination geometry at the metal center. Few examples of such species have been as yet reported, though they can find interesting applications for many purposes, such as the deliberate construction of homoor heterometallic networks with specific topologies, or the assembly of hydrogen-bonded frames, by using suitable (hydrogen-donor) organic molecules as spacers. Squareplanar metal-porphyrinate complexes bearing four donor 4-pyridyl substituents on the macrocycle have been used, for instance, for the deliberate assembly of cooperite-like networks[6] and of other types of bimetallic frames.[7] Some other metal-containing TMligands∫ have been employed,[8] such as the anionic square-planar [Pt(CN)4] [9] and digonal [M(CN)2] (M Ag, Au)[10] species. We have prepared as a new building block the neutral complex trans-[RuCl2(pyz)4] (1; pyz pyrazine): it was obtained by reacting [RuCl2(dmso)4] in toluene with a large 3487 ± 3494; G. Baum, E. C. Constable, D. Fenske, C. E. Housecroft, T. Kulke, Chem. Eur. J. 1999, 5, 1862 ± 1873; E. E. Simanek, S. Qiao, I. S. Choi, G. M. Whitesides, J. Org. Chem. 1997, 62, 2619 ± 2621; O. Mamula, A. von Zelewsky, G. Bernardinelli, Angew. Chem. 1998, 110, 302 ± 305; Angew. Chem. Int. Ed. 1998, 37, 289 ± 293; R. K. Castellano, C. Nuckolls, J. Rebek, Jr. J. Am. Chem. Soc. 1999, 121, 11156 ± 11163; T. Kondo, K.-I. Oyama, K. Yoshida, Angew. Chem. 2001, 113, 918 ± 922; Angew. Chem. Int. Ed. 2001, 40, 894 ± 897; C. R. Woods, M. Benaglia, F. Cozzi, J. S. Siegel, Angew. Chem. 1996, 108, 1977 ± 1980; Angew. Chem. Int. Ed. Engl. 1996, 35, 1830 ± 1833; L. J. Prins, P. Timmerman, D. N. Reinhoudt, J. Am. Chem. Soc. 2001, 123, 10153 ± 10163. [4] M. A. Masood, E. J. Enemark, T. D. P. Stack,Angew. Chem. 1998, 110, 973 ± 977; Angew. Chem. Int. Ed. 1998, 37, 928 ± 932; J.-M. Vincent, C. Philouze, I. Pianet, J.-B. Verlhac, Chem. Eur. J. 2000, 6, 3595 ± 3599; X. Shi, J. C. Fettinger, M. Cai, J. T. Davis,Angew. Chem. 2000, 112, 3254 ± 3257; Angew. Chem. Int. Ed. 2000, 39, 3124 ± 3127; X. Shi, J. C. Fettinger, J. T. Davis, J. Am. Chem. Soc. 2001, 123, 6738 ± 6739; L. J. Prins, J. Huskens, F. de Jong, P. Timmerman, D. N. Reinhoudt, Nature 1999, 398, 498 ± 502. [5] J. N. H. Reek, A. Kros, R. J. M. Nolte, Chem. Commun. 1996, 245 ± 247; J. A. A. W. Elemans, R. de Gelder, A. E. Rowan, R. J. M. Nolte, Chem. Commun. 1998, 1553 ± 1554; S. J. Holder, J. A. A. W. Elemans, J. J. J. M. Donners, M. J. Boerakker, R. de Gelder, J. Barbera¬ , A. E. Rowan, R. J. M. Nolte, J. Org. Chem. 2001, 66, 391 ± 399. [6] C. S. Wilcox, L. M. Greer, V. Lynch, J. Am. Chem. Soc. 1987, 109, 1865 ± 1867; S. C. Zimmerman, M. Mrksich, M. Baloga, J. Am. Chem. Soc. 1989, 111, 8528 ± 8530; M. Harmata, C. L. Barnes, S. R. Karra, S. Elahmad, J. Am. Chem. Soc. 1994, 116, 8392 ± 8393; F.-G. Kl‰rner, J. Panitzky, D. Bl‰ser, R. Boese, Tetrahedron 2001, 57, 3673 ± 3687. [7] a) D. Witt, J. Lagona, F. Damkaci, J. C. Fettinger, L. Isaacs, Org. Lett. 2000, 2, 755 ± 758; b) L. Isaacs, D. Witt, J. Lagona, Org. Lett. 2001, 3, 3221 ± 3224. [8] Selected references: M. Fujita, J. Yazaki, K. Ogura, J. Am. Chem. Soc. 1990, 112, 5645 ± 5647; M. Fujita, D. Oguro, M. Miyazawa, H. Oka, K. Yamaguchi, K. Ogura, Nature 1995, 378, 469 ± 471; S.-Y. Yu, T. Kusukawa, K. Biradha, M. Fujita, J. Am. Chem. Soc. 2000, 122, 2665 ± 2666; K. Umemoto, K. Yamaguchi, M. Fujita, J. Am. Chem. Soc. 2000, 122, 7150 ± 7151; N. Fujita, K. Biradha, M. Fujita, S. Sakamoto, K. Yamaguchi, Angew. Chem. 2001, 113, 1768 ± 1771; Angew. Chem. Int. Ed. 2001, 40, 1718 ± 1721. [9] D. Schubert, C. Tziatzios, P. Schuck, U. S. Schubert, Chem. Eur. J. 1999, 5, 1377 ± 1383; T. M. Laue, Methods Enzymol. 1995, 259, 427 ± 452. [10] Coordination compounds with N and O ligands: L. D. Pettit, M. Bezer Coord. Chem. Rev. 1985, 61, 97 ± 114; K. Matsumoto, H. Moriyama, K. Suzuki Inorg. Chem. 1990, 29, 2096 ± 2100; T. G. Appleton, D. R. Bedgood, Jr., J. R. Hall Inorg. Chem. 1994, 33, 3834 ± 3841.