Cu(2-methylpyrazine-5-carboxylate)(2) hydrate: a metal-containing-ligand for the construction of organic-inorganic framework materials. Four new one-, two- and three-dimensional mixed-valent Cu-I-Cu-II coordination polymers

The copper containing building block, Cu(C6H2N2O2)(2).H2O (1) was used in t he synthesis of four new mixed-valent organic-inorganic coordination polyme rs, each of which adopted a different structural motif. Synthesis, X-ray st ructure determinations, thermogravimetric analyses and magnetic properties are presented. The reaction between 1 and CdCl2, afforded a one-dimensional chain structure, [Cu(C6H5N2O2)(2)(H2O)(2)Cu2Cl2(H2O)(2)](n) (2). When CdCl 2 was replaced by CuCl, the reaction yielded a polymer, [Cu(C6H5N2O2)(2)(H2 O)(2)Cu2Cl2(H2O)(2)](n) having the same empirical formula, but a completely different two-dimensional framework (3). The reaction of CdBr2 and 1 resul ted in the formation of two different coordination polymers: [Cu(C6H5N2O2)( 2)(H2O)(2)Cu(C6H5N2O2)(2)Cu2Br2.3(H2O)](n) (4) as a minor phase and [Cu(C6H 5N2O2)(2)Cu2Br2.](n) (5) as the major phase. Compound 4 adopts a two-dimens ional structure, while 5 is three-dimensional. The structural classificatio n of these Cu(I) containing coordination polymers is discussed. These new c oordination polymers feature mixed-valent Cu(I)-Cu(II) frameworks and exhib it impressive thermal stability (the frameworks collapse between 236 and 24 6 degreesC). The magnetic susceptibilities for 2, 3 and 5 followed the Curi e law, indicating simple paramagnetic behavior. (C) 2001 Elsevier Science B .V. All rights reserved.