希土胺羧酸配合物的研究——Ⅲ.吡啶-2,6-二甲酸钕配合物{[Nd(HDPA)(DPA)(H_2O)_2]·4H_2O}_n合成及其晶体结构

STUDIES ON RARE EARTH COMPLEXES OF AMINOPOLYCARBOXYLIC ACID III. SYNTHESIS AND CRYSTAL STRUCTURE OF {[Nd(HDPA)(DPA)(H_2O)] ?4H2O}n COMPLEX

关于吡啶-2,6-二甲酸希土配合物晶体结构有Na_3[Ln(DPA)_3]·yNaClO_4·xH_2O类型的报道。本文合成了{[Nd(HDPA)(DPA)(H_2O)_2]·4H_2O}_n。配合物单晶并测定了其结构。 将硝酸希土溶液与吡啶-2,6-二甲酸以1:3的摩尔比混合,加入适量蒸馏水和四甲基铵盐,加热搅拌并滴加四甲基铵碱至吡啶-2,6-二甲酸溶解。冷却后调溶液pH至2,室温下放置数天得到单晶。

The complexes of {[Ln(HDPA)(DPA)(H2O)2] ?4H2O}n have been synthesized (Ln = Nd, Gd; H2DPA = dipicolinic acid )and studied by thermoanalysis and infrared spectroscopy. The crystal structure of {[Nd(HDPA)(DPA)(H2O)2] ?4H2O}n has been determined by single crystal diffraction. 3767 independent reflections vere collected, of which 1540 were used for structure refining. The final deviation factors of R and Rw equal to 0.059 and 0.067 respectively. Four formula units crystallize in a monoclinic cell with the dimensions a= 12.842A , b = 11.170 A, c= 13.984A, β= 102.11°. The space group is P2(1) / a. The result turns out that the complex is a one dimensional polymer in which the Nd atoms are connected by the bridging carboxyl groups. In the complex, every neodymium ion is coordinated by five carboxylate oxygen ,four of which-are from the four carboxylate groups of the two dipicolinic acid molecules and the other is the bridging carboxylate oxygen of dipicolinic ion in the pyr neighboring formula unit; the two nitrogen from the pyridine rings and the two oxygen from two water molecules ,so that coordination number of the neodymium is 9. The hydrogen on the undissociated carboxylic acid in the HDPA forms a hydrogen bond with the water molecule. rare earth dipicolinic acid crystal structure