SYNTHESIS AND CRYSTAL-STRUCTURE OF A POLYMERIC ERBIUM(III)-SODIUM(I) COORDINATION COMPLEX OF PICOLINIC-ACID N-OXIDE

A new Er(III)-Na(I) coordination polymer of stoichiometry [NaEr2L5(H2O )(6)(NO3)](NO3). 3.5H(2)O (HL = picolinic acid N-oxide) has been synth esized and characterized by single-crystal X-ray analysis. Crystals ar e triclinic, P (1) over bar with a = 9.823(2), b = 12.453(2), c = 20.6 43(4) Angstrom; alpha = 98.49(3), beta = 101.40(3), gamma = 108.69(3)d egrees; V = 2284(1) Angstrom(3); Z = 2. Of the two independent eight-c oordinate erbium(III) ions in this complex, one is surrounded by four bidentate chelating L ligands, and the other by one bidentate chelatin g L ligand, four aqua ligands and two anti-carboxylate oxygen atoms fr om two neighboring [ErL4] units. The sodium(I) ion is in a distorted o ctahedral environment, being coordinated by a unidentate nitrate anion , three aqua ligands and two anti-carboxylate oxygen atoms from two ad jacent [ErL4] units. The complex is built from zigzag chains of syn-an ti carboxylate-bridged erbium(III) moieties directed in the a directio n, which are cross-linked pairwise by aqua-bridged dimeric sodium(I) u nits. The resulting composite polymeric chains are further connected b y hydrogen bonds to form a three-dimensional network.