Crystal structure and thermal decomposition of tris(nitrato)di(N,N,N,N-tetrabutyl malonamide) complex of Pr(III)

The crystal structure of species Pr(NO3)(3)center dot 2TBMA (TBMA=N,N,N',N'-tetrabutyl malonamide) has been determined by X-ray diffraction. The compound crystallizes in the triclinic system, P1 space group, a=1.318 5(l 8) nm, b=1.449(2) nm, c=1.494(2) nm, alpha=70.03(2)degrees, beta=71.53(2)degrees, V=83.75(2)degrees, V=2.546(6) nm(3), Z=2, M-x =979.97, D-c=1.278 g center dot cm(-3), F(000)=1 032, R-1=0.054 7. In each molecule, the metal ion is 10-coordinate, being bonded to two nearly coplanar bidentate TBMA ligands and three bidentate nitrate ions, two of them located on each side of the plane defined by the TBMA ligands and the third one crossing the plane. The geometry can be best described in terms of pentagonal bipyramid with each bidentate nitrate occupying one site. The two coordinated C=O groups in TBMA are not parallel, the O(1)-C(1)... C(3)-O(2) and O(3)-C(20)... C(22)-O(4) Lorsion angles are 129.73 degrees and -48,43 degrees respectively. The absorption bands belonging to the coordinated carbonyl vibration split into 1577.96 and 1608.43 cm(-1) respectively, which is caused by the different environment. The thermal decornposition of the complex is in three steps.