[PD(HL)CL-2] AND [PDL2], WHERE HL IS 2-(3-PYRAZOLYL)PYRIDINE

The complexes cis-[Pd(HL)Cl-2] {dichloro[2-(3-pyrazolyl-N-2)pyridine-N ] palladium(II), [PdCl2(C8H7N3)]} and trans-[PdL2] bis[2-(3-pyrazolyl- N-2)pyridinato-N]palladium(II), [Pd(C8H6N3)(2)]} were isolated as bypr oducts from preparations of palladium(II) complexes with the podand li gand tris[3-(2-pyridyl)pyrazol-1-yl]-hydroborate, [HBL3](-). Both have square-planar coordination geometries. In cis-[Pd(HL)Cl-2], the Ligan d HL acts as a neutral bidentate chelate. In [PdL2], which has a trans geometry, the pyrazole N-1 position is deprotonated. This has two con sequences: (a) steric interference with the pyridyl H-6 proton of the alternate ligand is removed, and (b) inter-ligand intramolecular hydro gen bonding occurs between the pyridyl H-6 proton and the deprotonated pyrazolyl N-1 atom.