ELSEVIER I I Phenobarbiturate Complexes of Copper(II). Crystal Structure of Na2[Cu(phenobarbiturate) 4] Complex: A Symmetric Square Planar CuN4 Chromophore I. Sevilla, R. Ortiz, L. PereU6, J. Borr~s, S. Garcia-Granda, and A. Aguirre IS, RO, LP, JB. Departamento de Quimica Inorgdnica, Facultad de Farrnacia, Universidad de Valencia, Burjassot, Valencia, Spain.--SGG, AA. Universidad de Oviedo, Oviedo, Spain ABSTRACT The x-ray crystal structure of Na2[Cu(phenobarbiturate) 4] has been determined, in spite of the difficulties in maintaining single crystals. The complex crystallizes in space group P4/n cc with Q o a 3 a = 16.790(7) A, b = 16.790(7) A, c = 20.56(1) A, V= 5796(6) A, and Z = 4. The structure has been refined to R = 0.090. The Cu(II) ion is coordinated to four deprotonated phenobarbiturate ligands in a symmetric square planar geometry. The four Cu-N bond distances are 1.96(1) A and the N-Cu-N bond angles are exactly 90.0 °. The Na ions are surrounded by four carbonyl oxygen atoms from four phenobarbiturate ligands and four solvent water oxygen atoms in a cubic geometry. The interpretation of the spectral properties previously reported is related to the crystal structure. INTRODUCTION The complex formation between the barbituric derivatives and metal ions has been extensively studied since Parri [1] proposed the reaction between the Address reprint requests to: Dr. J. Borras, Departamento de Ouimica Inorg~nica, Facultad de Farmacia, Universidad de Valencia, Avda. Vicent Andres Estelles s/n, 46100-Burjassot, Valencia, Spain. Journalof lnorganicBiochemistry, 57, 147-155 (1995) © 1995 Elsevier Science Inc., 0162-0134/95/$9.50 655 Avenue of the Americas, NY, NY 10010 SSDI 0162-0134(94)00023-4