Metal-containing ligands for mixed-metal polymers:: Novel Cu(II)-Ag(I) mixed-metal coordination polymers generated from [Cu(2-methyipyrazine-5-carboxylate)2(H2O)]•3H2O and silver(I) salts

One Cu(II)-containing ligand and two Cu(II)-Ag(I) mixed-metal coordination polymers have been synthesized. [Cu(2-methylpyrazine-5-carboxylate)(2)(H2O)]. H2O (1) was obtained as a molecular complex with two uncoordinated nitrogen donors by the reaction of 2-methylpyrazine-5-carboxylate with CuCl2. 2H(2)O in water. Compound 1 crystallized in the triclinic space group P (1) over bar, with a = 10.498(2) Angstrom, b = 11.000(2) Angstrom, c = 8.1424(16) Angstrom, alpha = 98.33(3)degrees, beta = 101.83(3)degrees, gamma = 66.68(3)degrees, and Z = 2. Reactions of 1 with silver(I) salts have been studied. Two Cu(II)-Ag(I) mixed-metal coordination polymers, namely, Ag[Cu(2-methylpyrazine-5-carboxylate)(2). (H2O)(2)](BF4) (2) and Ag[Cu(2-methylpyrazine-5-carboxylate)(2).(H2O)(2)](NO3) (3), have been generated by treating 1 with AgBF4 and AgNO3, respectively. Compound 2 crystallized in the monoclinic space group C2/c, with a = 25.827(5) Angstrom, b = 9.6430(19) Angstrom, c = 7.4525(15) Angstrom, beta = 94.74(3)degrees, and Z = 4. Compound 3 also crystallized in the monoclinic space group C2/c, with a = 25.855(5) Angstrom, b = 9.782(2) Angstrom, c = 7.1201(14) Angstrom, beta = 96.90(3)degrees, and Z = 4. The main structural feature in both 2 and 3 is a zigzag Cu(II)-Ag(I) mixed-metal chain, in which the alternating Cu(II) and Ag(I) centers are linked by 2-methylpyrazine-5-carboxylate spacers. The effect of the nitrate counterion was illustrated by compound 3, in which a novel [Ag+... NO3-] coordination chain has been found which acts as the connector to cross-link the one-dimensional zigzag chains into a three-dimensional network: In addition, an identical interchain O-H ... O hydrogen bonding system has been found in both 2 and 3 and has been shown to play a significant role in directing the alignment of the one-dimensional mixed-metal polymer chains in the crystalline state. The magnetic susceptibilities of 2 and 3 were measured and found to follow the Curie law (mu(eff) = 1.85 for 2 and 1.83 for 3).