New selective nickel(II)-N3 nitrogen bond in adenine: synthesis and structure of [(tren)(adenine)(monochloro) nickel(II)] chloride and [(tren)(imidazole)(monoaqua) nickel(II)] dichloride

• Published in: Journal of Crystallographic and Spectroscopic Research 1993-02, Vol.23 (2), p.119-131
• Main Authors: MARZOTTO, A, CLEMENTE, D. A, CICCARESE, A, VALLE, G
• Format: Article
• Language: English
• Subjects: ADENINES; AMINES; ANTIMETABOLITES; AROMATICS; AZAARENES; AZOLES; BOND ANGLE; BOND LENGTHS; CHEMICAL BONDS; CHLORIDES; CHLORINE COMPOUNDS; COHERENT SCATTERING; COMPLEXES; Condensed matter: structure, mechanical and thermal properties; CRYSTAL STRUCTURE; CRYSTALLOGRAPHY; DIFFRACTION; DIMENSIONS; DRUGS; Exact sciences and technology; HALIDES; HALOGEN COMPOUNDS; HETEROCYCLIC COMPOUNDS; IMIDAZOLES; Inorganic compounds; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LENGTH; LIGANDS; MAGNETIC RESONANCE; Metal complexes; MOLECULAR STRUCTURE; NICKEL COMPLEXES; NITROGEN COMPLEXES; NUCLEAR MAGNETIC RESONANCE; NUCLEIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; Physics; PURINES; RESONANCE; SCATTERING; SPECTROPHOTOMETRY; SPECTROSCOPY; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; SYNTHESIS; TOXICITY; TRANSITION ELEMENT COMPLEXES 400201 > Chemical & Physicochemical Properties; X-RAY DIFFRACTION
• ISSN: 0277-8068; 2374-8001; 1572-8854
• DOI: 10.1007/BF01195446

With the aim to obtain further insight into the nature of the Ni(II)-nitrogen bond in complexes with nucleobases, we have synthesized two novel Ni(II) ternary complexes constituted by Ni(II), tris(2-aminoethyl)amine (tren) and neutral adenine (AdH) or imidazole (ImH). The reaction of NiCl sub(2)-6H sub(2)O with tren and imidazole yields the ternary [Ni(tren)(ImH)(H sub(2)O)]Cl sub(2)-H sub(2)O complex and the same reaction with adenine instead of imidazole gives the ternary [Ni(tren)(AdH)Cl]Cl complex. The complexes have been studied by spectrophotometric and spectroscopic measurements and by X-ray diffraction. The ternary complex of adenine is monoclinic, space group C2/c, and exhibits a pseudo-octahedral geometry, being Ni(II) coordinated to the four nitrogen atoms of the tetradentate tren ligand, to a Cl super(-) ion and to the pyrimidine N3 site of a neutral adenine. Such an exclusive Ni-N3 bonding [2.081(4) angstrom] is now reported for the first time. The ternary complex of imidazole is monoclinic, space group P2 sub(1)/n. Its pseudo-octahedral geometry is similar to that found in the above adenine complex although a water molecule instead of a Cl super(-)ion is now present in the coordination sphere. In fact, Ni(II) is coordinated to tetradentrate tren, to the imidazole N1 nitrogen and to a water molecule. Electronic and super(1)H NMR spectra in solution indicate that the octahedral structures found in the solid state are substantially maintained in solution. Furthermore, the present investigation suggests that the adenine Ni-N3 and imidazole Ni-N1 bonds have the same chemical nature, involving mainly sigma - and only partially pi -bonding. The Ni-N3 bonding is discussed in connection with biological implications and possible applications.