Synthesis, spectroscopy and magnetic properties of transition-metal complexes with imidazol-2-yl-methyl[N-(n-butyl)amino]-diphenylphosphine oxide (2-izmape) – Structure of [Cu(2-izmape)2](BF4)2 complex

A series of three tetrafluoroborate coordination compounds of bioactive imidazol-2-yl-methyl[N-(n-butyl)amino]-diphenylphosphine oxide (2-izmape) ligand, with the following stoichiometries [Cu(2-izmape)2](BF4)2 and [M(2-izmape)2(BF4)2], M = Ni and Co, were obtained and studied. Stoichiometry and geometry of the compounds was confirmed by spectroscopic and magnetic studies as well as by elemental analyses. In particular, the crystal structures of the copper(II) compound was determined by X-ray diffraction method. The 2-izmape ligand has a potential capacity to coordinate to metal ions by following atoms: phosphoryl oxygen, amino nitrogen and imidazolyl nitrogen. In studied compounds, 2-izmape adopts the didentate N,N-coordination mode, bonding metal centers through the imidazolyl and amino nitrogen atoms. Phosphoryl oxygen atom does not participate in coordination. All complexes are monomeric with square planar (Cu) or octahedral (Ni, Co) environment of metal ions. The magnetic studies (1.8–300 K) suggest the possibility of very weak antiferromagnetic (Co) and ferromagnetic (Ni) interaction between paramagnetic centers in crystal lattice. Copper centers are magnetically isolated.

Graphical abstractThe tetrafluoroborate transition metal complexes with new class of aminophosphonate ligand derived from imidazole, i.e. the imidazol-2-yl-methyl[N-(n-butyl)amino]-diphenylphosphine oxide (2-izmape) ligand were prepared and studied spectroscopically and magnetically. In particular, the crystal structure of [Cu(2-izmape)2](BF4)2 was determined by the X-ray diffraction method. The complexes are monomeric, in which 2-izmape acts as N,N-chelate ligand. The magnetic studies indicate weak antiferromagnetic interaction between paramagnetic centers in crystal lattice. Copper centers are magnetically isolated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The transition metal complexes with aminophosphonate ligand have been prepared. ► The complexes have been investigated by spectroscopy and magnetic measurements. ► The structure of Cu(II) complex was determined by the X-ray diffraction method. ► The ligand acts as N,N-chelate producing monomeric four (Cu) and six-coordinated (Ni, Co) complexes. ► The magnetic studies were discussed in the light of the proposed mononuclear structure of obtained species.