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metal-organic compounds
The complexes cis-[Pd(HL)Cl2] {dichloro[2-(3-pyrazolyl-N2)pyridine-N]palladium(II), [PdCl2(C8H7N3)]} and trans-[PdL2] {bis[2-(3-pyrazolyl-N2)pyridinato-N]palladium(II), [Pd(C8H6N3)2]} were isolated as by-products from preparations of palladium(II) complexes with the podand ligand tris[3-(2-pyridyl)pyrazol-1-yl]hydroborate, [HBL3]-. Both have square-planar coordination geometries. In cis-[Pd(HL)Cl2], the ligand HL acts as a neutral bidentate chelate. In [PdL2], which has a trans geometry, the pyrazole N1 position is deprotonated. This has two consequences: (a) steric interference with the pyridyl H6 proton of the alternate ligand is removed, and (b) inter-ligand intramolecular hydrogen-bonding occurs between the pyridyl H6 proton and the deprotonated pyrazolyl N1 atom.