Geometry and bonding of nitro- an azido-groups in palladium(II) four-co-ordinate complexes containing terdentate ligands

Abstract

The crystal structures of the following palladium(II) complexes: (I)[NO₂Pd(dien)]NO₃, (II)[NO₂Pd(Et₄dien)]- NO₃, and (III)[N₃Pd(Et₄dien)]NO₃(dien = diethylenetriamine) have been determined by Patterson and Fourier methods. Crystal data are: (I), monoclinic, space group P2₁/c, Z= 4, a= 11.627(7), b= 7.617(6), c= 17·380(9)Å, β= 133.77(5)°: (II), orthorhombic, space group P2₁2₁2₁, Z= 4, a= 21.825(9), b= 10.977(7), c= 8.233(6)Å; (III), orthorhombic, space group P2₁2₁2₁, Z= 4, a= 20.167(9), b= 11.262(6). c= 8.644(6)Å. Anisotropic least-squares refinement reduced R to 0.034 (I) 0.052 (II), and 0.059 (III). The co-ordination geometry of the nitro-group is determined by the bulkiness of the terdentate ligand in such a way that NO₂^– is nearly parllel to the donar-atom plane in (I) and nearly normal to it in (II). A π contribution in the Pd–NO₂ and Pd–N₃ bonds seems to be excluded on the basis of structural parameters.